These access doors were developed to provide easy access into air ducts and units, and to provide a solid, leak proof door that is simple to install with self-adhesive template for the exact size of the round duct opening required. The insulated door has a smooth interior finish and has been tested to +20” W.G. and -10” W.G. with no leakage noted. The access doors are UL classified FHC 25/50.