Strata Density Fiberglass Air Filter [Set of 12] Size: 25" x 20" Protects HVAC coils from dirt for general air filtration applications with light to medium dust Constructed with a strong, chipboard frame bonded to AAF manufactured premium grade fiberglass media Coated with a light adhesive to increase the amount of dirt the filters can hold The chipboard filter frame, free of sharp edges Priced and sold by the case of 12