All the mechanics are identical to the XS2 model and consists of a downstream side valve system, with adjustable orifice, simple and extremely reliable. A flow of pilot air is channelled to the mouthpiece by injection, enhancing the performance.

The upper part of the body has a flow deviator that acts on the Venturi effect, with dive/pre-dive function.

Constantly reviewed over the years, this regulator has lots of admirers in the world due to the fact that it is extremely simple and strong, features that make it easy to use and result in low-cost maintenance. In any case, performance levels are high, although the calibration is regulated so that the inhalation effort is slightly greater than on the XS2, to prevent any free-flow possibility when it is used as a spare regulator. The air supply pressure can be adjusted between 9 and 10 bar, perfectly suited to all the Cressi first stages.