The AERO-Cell is a rigid air filter engineered to provide medium and high efficiency filtration combined with a prolonged life cycle. Its box filter construction eliminates the need for retainer and special external wire media supports. The perimeter frame is constructed of high strength, corrosion resistant galvanized steel. Beverage board die cut faceplates are bonded to both the air entry and exit sides to maintain filter integrity. Each AERO-Cell utilizes a high-density filter media composed of ultra-fine glass fibers laminated to reinforced, high strength nylon backing. UL Class 2.