This pressure regulator is made of NSF-approved Acetal with port sizes of 1/4" (R25) and 3/8" (R45). Both have 1/4" gauge port threads. The maximum supply pressure is 125 psi and the temperature range is 40 ºF to 125 ºF. The spring pressure ranges are 0-25 psi, 0-60 psi, and 0-125 psi. This Regulator is recommended for compressed air. The 1/4" regulator is relieving and the 3/8" is non-relieving.