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 Envoy II is an incredible value, matching or exceeding the performance of regulators costing much more. If you are looking for an economical regulator that doesn't compromise on performance or reliability, you can't do better than the Envoy II.