Diaphragm mounting design ensures constant, uniform pressure control - even during peak loads! Non-adjustable, patented shut-down safety. Left-threaded high pressure ports to prevent low pressure outlet use. Internal relief valve (when delivery pressure exceeds set pressure by 15 PSIG). Quad-ring seal (no washer required). Inlet nipple particle filter. FYI: Pressure tested to insure in-field reliability. Set to blow off at 55-65 PSIG. UL.