Technical Divers need redundant safety back-ups on most all their equipment to assure the safest dive techniques allowed. A First-Stage Regulator should work well when it is maintained properly, yet if it does malfunction added safety features can make the difference between a controlled emergency and a diving accident. Incorporating a safety relief valve on your First-Stage regulator allow an over pressurization of the 2nd-Stage Hose nearly imposable. This Compact Over-Relief Valve (OPV) is designed to releases pressure in the event of an over pressurization of the first stage regulator. Easy to install into a standard 3/8-24 UNF low pressure regulator port.