15psi Pressure Relief ValveWhen pressurizing your Spike FLEX+ you'll always want to use a pressure relief valve (PRV). This will prevent the tank from being over pressurized and causing a potential failure to occur. It will keep your tank below the 15psi max working pressure rating. The PRV also has a handy bleeder pull ring to release built up pressure. Specs: 15psi release 1 4"npt threads **This accessory is to only be used with the FLEX+ or the upgraded high pressure lid**