The Deringer 40/50 Relief Valve uses a stainless steel body, piston seal and stainless steel sensing line and has been designed to be the smallest and lightest Relief Valve in the industry. Unlike previous relief valve designs, the piston seal does not use the body of the relief valve to align itself properly when closing and opening and instead uses the guide pin on the piston. This will aid in making the Relief Valve resistant to build up and binding. All components of the relief valve are lead free and meet the SDWA requirements.