{"product_id":"knockout-aluminum-double-door-backdraft-damper-bui","title":"Knockout Aluminum Double Door Backdraft Damper Built Damn Tough To Keep Airflow Crisp And Draft Free 51 By 48 Inch Heavy Duty Two Panel Vent Grille Made In Usa For Real Professionals","description":"\u003cdiv\u003eAluminum double flap dampener stops cold drafts in standard wall openings\u003cbr\u003e\n✔️ 51 by 48 inch aluminum double door seals vents against reverse draft flow \u003cp\u003eThis rugged aluminum double door backdraft damper functions as a reliable one way valve for standard residential and commercial ductwork. It installs directly into square rough openings to block cold air, dirt, and pests from sneaking into your HVAC loop when exhaust fans power down. Designed as a single precision machined unit, this white coated model delivers steady performance while handling high volume air movement without creating excessive static pressure.\u003c\/p\u003e ✅ Dual flap aluminum construction delivers solid resistance up to 2500 fpm peak velocity\u003cbr\u003e\n✅ Exact 51 inch outer height by 48 inch outer width matches standard 48 inch fan face measurements perfectly\u003cbr\u003e\n✅ Massive 12 9 square foot open area maintains unrestricted airflow through long duct runs\u003cbr\u003e\n✅ Solid 3 inch projection frame bolts securely into concrete or wood headers for permanent mounting\u003cbr\u003e\n✅ Corrosion resistant white coating withstands direct sun exposure without peeling or fading every season\u003cbr\u003e \u003cp\u003e💡 How does a double flap aluminum backdraft dampener actually block reverse air movement in high velocity exhaust systems?\u003cbr\u003e\n- Heavy gauge steel springs hold the dual aluminum panels open until fan spin slows past zero mph\u003cbr\u003e\n- Tight interlocking blade edges eliminate acoustic whine and heat loss during idle operational windows\u003cbr\u003e\n- Aligning the central pivot screw with the square duct core keeps the mechanical linkage responsive\u003cbr\u003e\n- Wiping dust off the hinge barrel regularly ensures the durable assembly remains handy for routine filter swaps\u003c\/p\u003e✝️\u003c\/div\u003e","brand":"Amazon","offers":[{"title":"Default Title","offer_id":49251037413611,"sku":"VXB007I9Z48O","price":870.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0662\/3268\/0683\/files\/61acfJfFEoL_ee5548ee-46c0-4b5a-a389-08bfeaff7f6d.jpg?v=1787079755","url":"https:\/\/vxb.com\/products\/knockout-aluminum-double-door-backdraft-damper-bui","provider":"VXB Bearings","version":"1.0","type":"link"}