{"title":"4-Inch Furnace Filters","description":"\u003cp\u003eEvery 4-inch furnace filter size Filterflow ships, in MERV 8 and MERV 11. Deep-pleated media filters for furnaces with a 4-inch cabinet, typically replaced every 6 to 12 months. Subscribe once — a year of filters, free FedEx shipping, and text reminders when it's time to swap.\u003c\/p\u003e\u003cp\u003eNeed a different depth? See \u003ca href=\"\/collections\/1-inch-furnace-filters\"\u003e1-inch filters\u003c\/a\u003e or \u003ca href=\"\/collections\/5-inch-furnace-filters\"\u003e5-inch Honeywell-compatible filters\u003c\/a\u003e.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDon't see your size?\u003c\/strong\u003e \u003ca href=\"\/pages\/contact\"\u003eContact us\u003c\/a\u003e with the dimensions printed on your current filter's frame, and we'll check whether we can get it for you.\u003c\/p\u003e","products":[{"product_id":"16x20x4-furnace-filter","title":"16x20x4 Furnace Filter","description":"\u003cdiv style=\"font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; color: #1a2b4a; line-height: 1.6; font-size: 15px;\"\u003e\n\u003cdiv style=\"background: #F3F5F9; border-left: 3px solid #B85838; padding: 16px 20px; margin: 0 0 24px; border-radius: 4px;\"\u003e\n\u003cp style=\"margin: 0 0 4px; font-size: 12px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: #8a3f25;\"\u003eFurnace Filter Subscription\u003c\/p\u003e\n\u003cp style=\"margin: 0; font-size: 16px; color: #1a2b4a; font-weight: 600;\"\u003eNominal size: 16x20x4. Actual dimensions: 15.5 x 19.5 x 3.75 inches (15½ × 19½ × 3¾).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size: 16px; line-height: 1.6; margin: 0 0 24px;\"\u003eA pleated 4-inch furnace filter subscription: a year's supply ships in one box, and whoever changes the filter — you, a tenant, a building contact — gets a text the day it's due, with a one-tap confirmation back to you. Set it once and never think about this filter again. Available in MERV 8 and MERV 11.\u003c\/p\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 8px;\"\u003eDoes this fit your furnace?\u003c\/h2\u003e\n\u003cp style=\"margin: 0 0 12px; color: #4a5970;\"\u003eThis filter is for HVAC slots labeled \u003cstrong style=\"color: #1a2b4a;\"\u003e16x20x4\u003c\/strong\u003e (the standard \"nominal\" size). The actual filter measures 15.5 x 19.5 x 3.75 inches — slightly smaller than nominal so it slides cleanly into the slot without binding.\u003c\/p\u003e\n\u003cp style=\"margin: 0 0 8px; color: #4a5970;\"\u003eTo confirm fit:\u003c\/p\u003e\n\u003col style=\"margin: 0 0 24px; padding-left: 24px; color: #4a5970;\"\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003ePull out your current filter from the unit.\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eLook for the size printed on the cardboard frame — typically the nominal size (16x25x4, 20x25x4, etc.).\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eIf you can't find a size label, measure the slot opening with a tape measure. The nominal size should be ½ inch larger than your slot dimensions in each direction.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 12px;\"\u003eSpecifications\u003c\/h2\u003e\n\u003cdiv style=\"background: #FFFFFF; border: 1px solid rgba(26,43,74,0.10); border-radius: 10px; overflow: hidden; margin: 0 0 24px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; width: 200px; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eNominal size\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e16x20x4 (16×20×4)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eActual dimensions\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e15.5 x 19.5 x 3.75 inches (15½ × 19½ × 3¾)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eFilter media\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003ePleated synthetic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eMERV options\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e8, 11 — \u003ca href=\"\/pages\/merv-guide\" style=\"color: #b85838; text-decoration: underline;\"\u003esee MERV guide\u003c\/a\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eReplacement frequency\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eTypically every 6–12 months. Pets, dust, or heavy use call for more frequent changes.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93;\"\u003eCompatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600;\"\u003eMost residential furnaces, central AC, and air handlers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Filterflow","offers":[{"title":"MERV 8 \/ 2-pack","offer_id":43372744343641,"sku":"16x20x4-M8-2P","price":86.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 3-pack","offer_id":43372744376409,"sku":"16x20x4-M8-3P","price":96.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 4-pack","offer_id":43372744409177,"sku":"16x20x4-M8-4P","price":101.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 2-pack","offer_id":43379317964889,"sku":"16x20x4-M11-2P","price":88.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 3-pack","offer_id":43379317997657,"sku":"16x20x4-M11-3P","price":98.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 4-pack","offer_id":43379318030425,"sku":"16x20x4-M11-4P","price":104.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0732\/2229\/1545\/files\/filter-flow-furnace-filter-subscription-merv-8-rectangle-2-pack.webp?v=1781011739"},{"product_id":"20x25x4-furnace-filter","title":"20x25x4 Furnace Filter","description":"\u003cdiv style=\"font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; color: #1a2b4a; line-height: 1.6; font-size: 15px;\"\u003e\n\u003cdiv style=\"background: #F3F5F9; border-left: 3px solid #B85838; padding: 16px 20px; margin: 0 0 24px; border-radius: 4px;\"\u003e\n\u003cp style=\"margin: 0 0 4px; font-size: 12px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: #8a3f25;\"\u003eFurnace Filter Subscription\u003c\/p\u003e\n\u003cp style=\"margin: 0; font-size: 16px; color: #1a2b4a; font-weight: 600;\"\u003eNominal size: 20x25x4. Actual dimensions: 19.5 x 24.5 x 3.75 inches (19½ × 24½ × 3¾).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size: 16px; line-height: 1.6; margin: 0 0 24px;\"\u003eA pleated 4-inch furnace filter subscription: a year's supply ships in one box, and whoever changes the filter — you, a tenant, a building contact — gets a text the day it's due, with a one-tap confirmation back to you. Set it once and never think about this filter again. Available in MERV 8 and MERV 11.\u003c\/p\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 8px;\"\u003eDoes this fit your furnace?\u003c\/h2\u003e\n\u003cp style=\"margin: 0 0 12px; color: #4a5970;\"\u003eThis filter is for HVAC slots labeled \u003cstrong style=\"color: #1a2b4a;\"\u003e20x25x4\u003c\/strong\u003e (the standard \"nominal\" size). The actual filter measures 19.5 x 24.5 x 3.75 inches — slightly smaller than nominal so it slides cleanly into the slot without binding.\u003c\/p\u003e\n\u003cp style=\"margin: 0 0 8px; color: #4a5970;\"\u003eTo confirm fit:\u003c\/p\u003e\n\u003col style=\"margin: 0 0 24px; padding-left: 24px; color: #4a5970;\"\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003ePull out your current filter from the unit.\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eLook for the size printed on the cardboard frame — typically the nominal size (16x25x4, 20x25x4, etc.).\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eIf you can't find a size label, measure the slot opening with a tape measure. The nominal size should be ½ inch larger than your slot dimensions in each direction.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 12px;\"\u003eSpecifications\u003c\/h2\u003e\n\u003cdiv style=\"background: #FFFFFF; border: 1px solid rgba(26,43,74,0.10); border-radius: 10px; overflow: hidden; margin: 0 0 24px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; width: 200px; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eNominal size\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e20x25x4 (20×25×4)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eActual dimensions\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e19.5 x 24.5 x 3.75 inches (19½ × 24½ × 3¾)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eFilter media\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003ePleated synthetic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eMERV options\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e8, 11 — \u003ca href=\"\/pages\/merv-guide\" style=\"color: #b85838; text-decoration: underline;\"\u003esee MERV guide\u003c\/a\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eReplacement frequency\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eTypically every 6–12 months. Pets, dust, or heavy use call for more frequent changes.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93;\"\u003eCompatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600;\"\u003eMost residential furnaces, central AC, and air handlers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Filterflow","offers":[{"title":"MERV 8 \/ 2-pack","offer_id":43372744441945,"sku":"20x25x4-M8-2P","price":92.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 3-pack","offer_id":43372744474713,"sku":"20x25x4-M8-3P","price":99.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 4-pack","offer_id":43372744507481,"sku":"20x25x4-M8-4P","price":111.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 2-pack","offer_id":43379318063193,"sku":"20x25x4-M11-2P","price":102.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 3-pack","offer_id":43379318095961,"sku":"20x25x4-M11-3P","price":113.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 4-pack","offer_id":43379318128729,"sku":"20x25x4-M11-4P","price":130.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0732\/2229\/1545\/files\/filter-flow-furnace-filter-subscription-merv-8-rectangle-2-pack.webp?v=1781011739"},{"product_id":"20x20x4-furnace-filter","title":"20x20x4 Furnace Filter","description":"\u003cdiv style=\"font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; color: #1a2b4a; line-height: 1.6; font-size: 15px;\"\u003e\n\u003cdiv style=\"background: #F3F5F9; border-left: 3px solid #B85838; padding: 16px 20px; margin: 0 0 24px; border-radius: 4px;\"\u003e\n\u003cp style=\"margin: 0 0 4px; font-size: 12px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: #8a3f25;\"\u003eFurnace Filter Subscription\u003c\/p\u003e\n\u003cp style=\"margin: 0; font-size: 16px; color: #1a2b4a; font-weight: 600;\"\u003eNominal size: 20x20x4. Actual dimensions: 19.5 x 19.5 x 3.75 inches (19½ × 19½ × 3¾).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size: 16px; line-height: 1.6; margin: 0 0 24px;\"\u003eA pleated 4-inch furnace filter subscription: a year's supply ships in one box, and whoever changes the filter — you, a tenant, a building contact — gets a text the day it's due, with a one-tap confirmation back to you. Set it once and never think about this filter again. Available in MERV 8 and MERV 11.\u003c\/p\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 8px;\"\u003eDoes this fit your furnace?\u003c\/h2\u003e\n\u003cp style=\"margin: 0 0 12px; color: #4a5970;\"\u003eThis filter is for HVAC slots labeled \u003cstrong style=\"color: #1a2b4a;\"\u003e20x20x4\u003c\/strong\u003e (the standard \"nominal\" size). The actual filter measures 19.5 x 19.5 x 3.75 inches — slightly smaller than nominal so it slides cleanly into the slot without binding.\u003c\/p\u003e\n\u003cp style=\"margin: 0 0 8px; color: #4a5970;\"\u003eTo confirm fit:\u003c\/p\u003e\n\u003col style=\"margin: 0 0 24px; padding-left: 24px; color: #4a5970;\"\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003ePull out your current filter from the unit.\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eLook for the size printed on the cardboard frame — typically the nominal size (16x25x4, 20x25x4, etc.).\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eIf you can't find a size label, measure the slot opening with a tape measure. The nominal size should be ½ inch larger than your slot dimensions in each direction.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 12px;\"\u003eSpecifications\u003c\/h2\u003e\n\u003cdiv style=\"background: #FFFFFF; border: 1px solid rgba(26,43,74,0.10); border-radius: 10px; overflow: hidden; margin: 0 0 24px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; width: 200px; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eNominal size\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e20x20x4 (20×20×4)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eActual dimensions\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e19.5 x 19.5 x 3.75 inches (19½ × 19½ × 3¾)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eFilter media\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003ePleated synthetic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eMERV options\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e8, 11 — \u003ca href=\"\/pages\/merv-guide\" style=\"color: #b85838; text-decoration: underline;\"\u003esee MERV guide\u003c\/a\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eReplacement frequency\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eTypically every 6–12 months. Pets, dust, or heavy use call for more frequent changes.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93;\"\u003eCompatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600;\"\u003eMost residential furnaces, central AC, and air handlers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Filterflow","offers":[{"title":"MERV 8 \/ 2-pack","offer_id":43372750340185,"sku":"20x20x4-M8-2P","price":88.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 3-pack","offer_id":43372750372953,"sku":"20x20x4-M8-3P","price":94.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 4-pack","offer_id":43372750405721,"sku":"20x20x4-M8-4P","price":103.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 2-pack","offer_id":43379318161497,"sku":"20x20x4-M11-2P","price":96.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 3-pack","offer_id":43379318194265,"sku":"20x20x4-M11-3P","price":105.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 4-pack","offer_id":43379318227033,"sku":"20x20x4-M11-4P","price":118.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0732\/2229\/1545\/files\/filter-flow-furnace-filter-subscription-merv-8-square-2-pack.webp?v=1781012842"},{"product_id":"16x25x4-furnace-filter","title":"16x25x4 Furnace Filter","description":"\u003cdiv style=\"font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; color: #1a2b4a; line-height: 1.6; font-size: 15px;\"\u003e\n\u003cdiv style=\"background: #F3F5F9; border-left: 3px solid #B85838; padding: 16px 20px; margin: 0 0 24px; border-radius: 4px;\"\u003e\n\u003cp style=\"margin: 0 0 4px; font-size: 12px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: #8a3f25;\"\u003eFurnace Filter Subscription\u003c\/p\u003e\n\u003cp style=\"margin: 0; font-size: 16px; color: #1a2b4a; font-weight: 600;\"\u003eNominal size: 16x25x4. Actual dimensions: 15.5 x 24.5 x 3.75 inches (15½ × 24½ × 3¾).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size: 16px; line-height: 1.6; margin: 0 0 24px;\"\u003eA pleated 4-inch furnace filter subscription: a year's supply ships in one box, and whoever changes the filter — you, a tenant, a building contact — gets a text the day it's due, with a one-tap confirmation back to you. Set it once and never think about this filter again. Available in MERV 8 and MERV 11.\u003c\/p\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 8px;\"\u003eDoes this fit your furnace?\u003c\/h2\u003e\n\u003cp style=\"margin: 0 0 12px; color: #4a5970;\"\u003eThis filter is for HVAC slots labeled \u003cstrong style=\"color: #1a2b4a;\"\u003e16x25x4\u003c\/strong\u003e (the standard \"nominal\" size). The actual filter measures 15.5 x 24.5 x 3.75 inches — slightly smaller than nominal so it slides cleanly into the slot without binding.\u003c\/p\u003e\n\u003cp style=\"margin: 0 0 8px; color: #4a5970;\"\u003eTo confirm fit:\u003c\/p\u003e\n\u003col style=\"margin: 0 0 24px; padding-left: 24px; color: #4a5970;\"\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003ePull out your current filter from the unit.\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eLook for the size printed on the cardboard frame — typically the nominal size (16x25x4, 20x25x4, etc.).\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eIf you can't find a size label, measure the slot opening with a tape measure. The nominal size should be ½ inch larger than your slot dimensions in each direction.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 12px;\"\u003eSpecifications\u003c\/h2\u003e\n\u003cdiv style=\"background: #FFFFFF; border: 1px solid rgba(26,43,74,0.10); border-radius: 10px; overflow: hidden; margin: 0 0 24px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; width: 200px; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eNominal size\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e16x25x4 (16×25×4)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eActual dimensions\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e15.5 x 24.5 x 3.75 inches (15½ × 24½ × 3¾)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eFilter media\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003ePleated synthetic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eMERV options\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e8, 11 — \u003ca href=\"\/pages\/merv-guide\" style=\"color: #b85838; text-decoration: underline;\"\u003esee MERV guide\u003c\/a\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eReplacement frequency\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eTypically every 6–12 months. Pets, dust, or heavy use call for more frequent changes.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93;\"\u003eCompatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600;\"\u003eMost residential furnaces, central AC, and air handlers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Filterflow","offers":[{"title":"MERV 8 \/ 2-pack","offer_id":43372750438489,"sku":"16x25x4-M8-2P","price":89.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 3-pack","offer_id":43372750471257,"sku":"16x25x4-M8-3P","price":94.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 4-pack","offer_id":43372750504025,"sku":"16x25x4-M8-4P","price":104.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 2-pack","offer_id":43379318259801,"sku":"16x25x4-M11-2P","price":96.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 3-pack","offer_id":43379318292569,"sku":"16x25x4-M11-3P","price":105.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 4-pack","offer_id":43379318325337,"sku":"16x25x4-M11-4P","price":118.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0732\/2229\/1545\/files\/filter-flow-furnace-filter-subscription-merv-8-rectangle-2-pack.webp?v=1781011739"},{"product_id":"20x24x4-furnace-filter","title":"20x24x4 Furnace Filter","description":"\u003cdiv style=\"font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; color: #1a2b4a; line-height: 1.6; font-size: 15px;\"\u003e\n\u003cdiv style=\"background: #F3F5F9; border-left: 3px solid #B85838; padding: 16px 20px; margin: 0 0 24px; border-radius: 4px;\"\u003e\n\u003cp style=\"margin: 0 0 4px; font-size: 12px; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: #8a3f25;\"\u003eFurnace Filter Subscription\u003c\/p\u003e\n\u003cp style=\"margin: 0; font-size: 16px; color: #1a2b4a; font-weight: 600;\"\u003eNominal size: 20x24x4. Actual dimensions: 19.5 x 23.5 x 3.75 inches (19½ × 23½ × 3¾).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size: 16px; line-height: 1.6; margin: 0 0 24px;\"\u003eA pleated 4-inch furnace filter subscription: a year's supply ships in one box, and whoever changes the filter — you, a tenant, a building contact — gets a text the day it's due, with a one-tap confirmation back to you. Set it once and never think about this filter again. Available in MERV 8 and MERV 11.\u003c\/p\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 8px;\"\u003eDoes this fit your furnace?\u003c\/h2\u003e\n\u003cp style=\"margin: 0 0 12px; color: #4a5970;\"\u003eThis filter is for HVAC slots labeled \u003cstrong style=\"color: #1a2b4a;\"\u003e20x24x4\u003c\/strong\u003e (the standard \"nominal\" size). The actual filter measures 19.5 x 23.5 x 3.75 inches — slightly smaller than nominal so it slides cleanly into the slot without binding.\u003c\/p\u003e\n\u003cp style=\"margin: 0 0 8px; color: #4a5970;\"\u003eTo confirm fit:\u003c\/p\u003e\n\u003col style=\"margin: 0 0 24px; padding-left: 24px; color: #4a5970;\"\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003ePull out your current filter from the unit.\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eLook for the size printed on the cardboard frame — typically the nominal size (16x25x4, 20x24x4, etc.).\u003c\/li\u003e\n\u003cli style=\"margin-bottom: 6px;\"\u003eIf you can't find a size label, measure the slot opening with a tape measure. The nominal size should be ½ inch larger than your slot dimensions in each direction.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2 style=\"font-size: 20px; font-weight: 600; color: #1a2b4a; letter-spacing: -0.015em; margin: 32px 0 12px;\"\u003eSpecifications\u003c\/h2\u003e\n\u003cdiv style=\"background: #FFFFFF; border: 1px solid rgba(26,43,74,0.10); border-radius: 10px; overflow: hidden; margin: 0 0 24px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; width: 200px; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eNominal size\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e20x24x4 (20×24×4)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eActual dimensions\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e19.5 x 23.5 x 3.75 inches (19½ × 23½ × 3¾)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eFilter media\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003ePleated synthetic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eMERV options\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003e8, 11 — \u003ca href=\"\/pages\/merv-guide\" style=\"color: #b85838; text-decoration: underline;\"\u003esee MERV guide\u003c\/a\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eReplacement frequency\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600; border-bottom: 1px solid rgba(26,43,74,0.06);\"\u003eTypically every 6–12 months. Pets, dust, or heavy use call for more frequent changes.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 11px 16px; color: #6b7a93;\"\u003eCompatibility\u003c\/td\u003e\n\u003ctd style=\"padding: 11px 16px; color: #1a2b4a; font-weight: 600;\"\u003eMost residential furnaces, central AC, and air handlers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Filterflow","offers":[{"title":"MERV 8 \/ 2-pack","offer_id":47329229013081,"sku":"20x24x4-M8-2P","price":84.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 3-pack","offer_id":47329229045849,"sku":"20x24x4-M8-3P","price":92.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 4-pack","offer_id":47329229078617,"sku":"20x24x4-M8-4P","price":101.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 2-pack","offer_id":47329229111385,"sku":"20x24x4-M11-2P","price":108.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 3-pack","offer_id":47329229144153,"sku":"20x24x4-M11-3P","price":128.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 4-pack","offer_id":47329229176921,"sku":"20x24x4-M11-4P","price":149.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0732\/2229\/1545\/files\/filter-flow-furnace-filter-subscription-merv-8-rectangle-2-pack.webp?v=1781011739"}],"url":"https:\/\/filter-flow.com\/collections\/4-inch-furnace-filters.oembed","provider":"Filterflow","version":"1.0","type":"link"}