Wilkerson® by Dixon® R21-03R dial Air Regulator Without Gauge, 3/8 in NPT/BSPP-G, 180 scfm Flow Rate, 0 to 160 psig Adjustable Pressure. Wilkerson® by Dixon® R21-03R dial Air Regulator Without Gauge, 3/8 in NPT/BSPP-G, 180 scfm, 0 to 160 psig Adjustable Pressure