{"product_id":"19-3-4x21-1-2x1-air-filter","title":"19 3\/4x21 1\/2x1 Aerostar Air Filter","description":"The 19 3\/4 x 21 1\/2 x 1 Aerostar fits a return that nominally would be called a 20x22x1 but actually measures 19 3\/4\" x 21 1\/2\" x 1\". Odd-sized returns like this appear in custom HVAC installations and certain regional construction markets where the original installer didn't size to a standard nominal opening. MERV 8 covers standard residential dust and pollen filtration. MERV 11 handles pet households and most common allergens. MERV 13 captures fine particulates including smoke, bacteria, and virus carriers - the grade for households with respiratory issues or in wildfire-affected regions. Pleated synthetic media with an electrostatic charge built into the fibers does the actual filtration work. The pleats give you substantially more surface area than a flat fiberglass filter at the same nominal size, extending the service life to a 60-to-90-day window in typical residential conditions. The electrostatic charge catches sub-micron particles where the physical weave alone reaches its limits. Manufactured in the USA by Con-Air Industries, Orlando, Florida. Cardboard frame, reinforced to maintain shape under blower suction. Odd-size filters benefit most from dimensional precision because an off-spec filter leaves gaps where unfiltered air bypasses the media entirely.","brand":"Aerostar","offers":[{"title":"MERV 8 \/ 6","offer_id":41902407155866,"sku":"P80S.0119M21H-6","price":129.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 2","offer_id":41902406992026,"sku":"P15S.0119M21H-2","price":42.99,"currency_code":"USD","in_stock":false},{"title":"MERV 13 \/ 2","offer_id":41902407024794,"sku":"P25S.0119M21H-2","price":46.34,"currency_code":"USD","in_stock":false},{"title":"MERV 8 \/ 4","offer_id":41902407057562,"sku":"P80S.0119M21H-4","price":87.99,"currency_code":"USD","in_stock":false},{"title":"MERV 11 \/ 4","offer_id":41902407090330,"sku":"P15S.0119M21H-4","price":84.99,"currency_code":"USD","in_stock":false},{"title":"MERV 13 \/ 4","offer_id":41902407123098,"sku":"P25S.0119M21H-4","price":87.16,"currency_code":"USD","in_stock":false},{"title":"MERV 8 \/ 2","offer_id":41902406959258,"sku":"P80S.0119M21H-2","price":44.99,"currency_code":"USD","in_stock":false},{"title":"MERV 11 \/ 6","offer_id":41902407188634,"sku":"P15S.0119M21H-6","price":124.99,"currency_code":"USD","in_stock":true},{"title":"MERV 13 \/ 6","offer_id":41902407221402,"sku":"P25S.0119M21H-6","price":124.99,"currency_code":"USD","in_stock":true},{"title":"MERV 8 \/ 12","offer_id":41902407254170,"sku":"P80S.0119M21H-12","price":249.99,"currency_code":"USD","in_stock":true},{"title":"MERV 11 \/ 12","offer_id":41902407286938,"sku":"P15S.0119M21H-12","price":239.99,"currency_code":"USD","in_stock":true},{"title":"MERV 13 \/ 12","offer_id":41902407319706,"sku":"P25S.0119M21H-12","price":261.74,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0591\/6937\/4362\/files\/19Mx21Hx1_MERV8_1pk.png?v=1790041601","url":"https:\/\/aerostarairfilters.com\/products\/19-3-4x21-1-2x1-air-filter","provider":"Aerostar Air Filters","version":"1.0","type":"link"}