ADH 100 Hinged with Camlock Closure & AD 100 Removable, Paired Camlocks. These Access Doors Meet SMACNA Requirements and Provide Quick, Simple Installation Whenever Duct Access Is Required. Available In Various Sizes to Meet All Access Requirements. Camlock Operation for A Positive Seal and Easy Opening. Meets SMACNA Construction Specifications for Systems Up to 2" W.G. & 4” W.G.