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
The RS-812S features a compact and reliable balanced piston first stage, offered in both yoke and DIN configurations. This compact, lightweight first stage produces instant delivery of air by way of two H.P. and four L.P. ports. The RS-812S also offers a breathing resistance adjustable control knob and universal swivel hose providing higher utility and superior performance.
Compact and reliable balanced piston first stage
Instant delivery of air and high airflow for superior performance