This Scubapro scuba diving regulator system has anti-freeze protection that increases breathing reliability in extreme temperatures. It has two opposing high-pressure ports that allow the first stage to be in either up or down position. This product has a metal barrel that is able to withstand long exposure to aggressive diving. It has a Venturi-Initiated Vacuum Assist (VIVA) dive and pre-dive switch, and a diver-adjustable inhalation effort knob.