This first stage epitomizes reliability and simplicity. Its standard Flow-By-Piston design is ideal for divers who don't want to get bogged down with an overwhelming amount of bits and pieces, but still want the peace of mind that comes with a sound piece of equipment. This first stage is equipped with Scubapro's Extended Thermal Insulating System (XTIS), which will keep your first stage functioning properly, even in frigid water.