Pressure Relief Valve 2" TC x .1 MPACustom made for StillDragon these SS 304 PRV's fit any 2" port on a boiler to ensure extra safety for pressure release in case of accident. Releasing at . 1 MPA or 14. 5 PSI. Stilldragon supplies all boilers as open to atmosphere and this path should never be restricted. Although these units are not strictly needed they provide an extra level of safety. PRV's are too heavy to ship in a 500gm satchel.