Pressure compensator features air permeability of 42 cubic feet/hour (1,200 liters/hour) at a pressure difference of minimum 70 mbar. Easy installation by drilling one 1.60 inch (41 mm) diameter hole. Sealing gasket (Nitrile Buna-N Rubber). Plastic PA66. Semipermeable membrane inside the plug to filter moisture and dust. Mounting thread M40 with union nut. Light-grey plastic finish. Polymeric material manufactured by DuPontâ„¢. Pressure differentials in a tightly sealed enclosure result from heat generated by electrical and electronic equipment within the enclosure and fluctuations of outside ambient temperature.