This is the XS Scuba Rebuildable & Adjustable OPV Over Pressure Valve Features: All stainless steel construction Easy to adjust from 150 to 250 psi Factory preset at 175 to 185 psi Machined Delrin cap protects the adjustment point Compact relief valve releases pressure in the event of an over pressurization of the first stage Fits standard 3/8-24 UNF low pressure regulator port Factory cleaned - Viton o-rings XS Scuba&';s Deluxe Over-Pressure Valve (OPV) is an adjustable all stainless-steel constructed valve. This compact relief valve is designed to releases pressure in the event of an over pressurization of the first stage regulator."