18x18x1 ElectraGOLD Lifetime Furnace Filter Electro-static polypropylene mesh Polyester media Extruded galvanized frame Galvanized wire mesh screening Made in USA High 94% Dust Arrestance and 165 grams Dust Holding Capacity PLUS Low 0.12" WG Air Resistance Rating Lifetime Warranty - Washable - Permanent - Electrostatic Our Gold Frame filters are made with a premium quality extruded stainless steel, gold anodized frame with a durable and attractive finish. The frame is 4 separate pieces with a single screw fastening each corner together making it strong and sturdy. Contain an EPA registered anti-microbial material to inhibit the mold and bacteria growth on the filter surface.