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
XS2/AC2 is the most inexpensive regulator in the Cressi range. The XS2 2nd stage comes with the traditionalCressi AC2 piston 1st stage. Constantly reviewed over the years, this regulator haslots of admirers in the worlddue to the fact that it isextremely simple and strong, features that make it easy to use and result in low-cost maintenance. The body of the 2nd stage istraditionally sized, made from hi-tech polymers and with a lateral valvedownstream systemwith adjustable orifice, simple andextremely reliable. A flow of pilot air is channelled to the mouthpiece by injection,enhancing the performance. The 2nd stage comes with a aflow deviatorthat acts on the Venturi effect, withdive/pre-dive function. In any case, performance levels are high, and it is suitable for any kind of dive. XS2 comes with the traditionalCressi AC2 piston model. This is a non-balanced first stage with such high performance that it can be compared to lots of excellent balanced models. The small number of components, the low weight and the excellent materials make itthe strongest Cressi first stages, and the most steadfast to maltreatment, a real “working horse” amongst regulators. An ingenious bush system allowseasy and rapid external regulation of the intermediate pressure.