This compact safety device activates to release excess gas pressure if the pressure exceeds a predetermined value. Ordinarily used with SCUBA regulators to protect the low-pressure output (aka intermediate pressure, aka IP) by the first stage regulator, over pressure is typically caused by the wear of the first stage regulator high pressure seat. This reduces risk of a hose rupture or second stage regulator failure. This particular item is rebuildable with an adjustable release pressure between 150 to 250 psi and a factory preset release pressure of 175 to 185 psi. Screws in to any standard 3/8-inch low pressure regulator port and is factory cleaned with oxygen compatible O-rings. It features stainless steel construction and a machined Delrin cap to protect the adjustment point.

To provide better drysuit insulation than their back gas breathing mixture would, divers sometimes carry a small pony containing argon or air with just a first stage regulator and a low pressure drysuit inflator hose. However, on dedicated drysuit inflation systems there is no regulator second stage to provide relief should the high pressure seat fail. Without a way to relieve the pressure, the drysuit could begin inflating rapidly or the low pressure hose could rupture. Another common application is in systems such as stage/bailout regulators and rebreathers where the second stage or ADV has been locked off with an inline shutoff. The over-pressure relief valve provides the same fail-safe function as a normal regulator second stage.