New Case of (12) Protect Plus 20x30x1 Air Furnace Filter Hvac Filters 8919912 445 utilizing the Purolator Monobond concept of a one-piece frame sealed to the media using heat and pressure. Fiberglass media is evenly coated with a gel adhesive to prevent finer particle migration. Full depth loading and high dust holding capacity. Filter media has a skin backing and is evenly coated with a gelled adhesive. FIBERGLASS Size Ins.=20 x 30 x 1