Aqualung Helix Compact PRO RegulatorFirst stage Balance diaphragm provides consistence performance T shape body for streamlined hose positioning In line ergonomic Venturi knob provides precise breathing adjustment, even while wearing gloves Second stage The Helix octopus is pneumatically balanced resulting in smooth and easy breathing A heat exchanger (patented) which surrounds the valve mechanism, dissipates the cold caused by gas expansion while drawing in the warmth of the ambient