Scubapro Evo Scuba Diving Regulator High Performance, Reliable Scubapro Technology and Value Superior Ultra-High Airflow System, Maximum Performance in All-Temperatures & Conditions Internal Parts Fully Insulated to Dramatically Improve Cold Water Performance Air-Balanced Flow-Thru-Piston Design, Balanced Composite/Stainless Steel Flow-Thru-Piston Diver-Adjustable Inhalation Effort, Diver-Adjustable Venturi-Initiated Vacuum Assist (VIVA)