Employs solid piston, balanced poppet for excellent performance, longer life. Port size is 3/8" NPTF. 2-gauge parts provided, 1 pressure gauge included. Maximum operating pressures are 250 P.S.I. primary, 2 to 125 P.S.I. secondary. 65 SCFMwith 100 P.S.I. inlet pressure. 1 per box.