Dyn-O-Mate Clamshell style Access Doors are available insulated or uninsulated and tested to withstand 20'' W.G. positive pressure & 10'' of negative pressure. They feature a closed Cell Neogasket and a bond to the inside plate that prevents leakage. Conical Springs between the two plates provides for easy installation and high impact plastic knobs are designed to avoid stripping and allow a tool-free operation. A template for duct-opening cut out is supplied to insure proper hole size.