Wilkerson® by Dixon® Regulator, High Pressure Self-Relieving Standard, series: R26, 1/2 in NPT/BSPP-G, 185 scfm, 0 to 250 psi Adjustable, 32 to 150°F, Zinc. Wilkerson® by Dixon® R26-04RH High Pressure Self-Relieving Standard Regulator Without Gauge, 1/2 in NPT/BSPP-G, 185 scfm