Clack Corporation introduces a revolutionary design for Dome Hole Tanks. The tanks have a large dome opening with a proprietary coarse thread design. Opens easily to refill media as needed and is easy to clean, allowing no media to be trapped in threads. The plug has two safety lock positions to help prevent an accidental discharge if the tank is not properly depressurized. When the tank is depressurized, press in on the center of the plug to disengage the lock before unthreading the plug.