You cannot breathe directly out of a scuba tank because of the high pressure. A regulator reduces pressure to safe a level that can be inhaled by the diver. A diving regulator has two parts: the First Stage reduces the tank pressure and connects it to the Second Stage which contains the mouthpiece for breathing
Full face mask compatible with conventional regulators. 3 DIN ports, two of which are dedicated to fit adapters for conventional regulators (once mouthpiece is removed). Remaining port is ready to fit comm. unit.