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 Onyx II, is the sealed version of the 2011 Scubalab Testers Choice regulator, the Onyx. With the same attractive finish and outstanding performance as the Onyx regulator, the Onyx II fills the need for those that find themselves in cooler water.