... .5",3",4",6". Bottom Brass Connection Stainless Steel Oil Filled Pressure Gauge 1. Diameter: 1 ½", 2", 2 ½ ",3",4",6";2 ... ;3.Window:polycarbonate;4.Internal: brass, stainless steel;5.Inlet thread:1/8", 1/4", 3/8",1/2",NPT,BSPT ... customers order.9.Oil composing:glyceine, silicone oil;10.Accuracy: 2.5%,1.6%,1%. Bottom Brass Connection Stainless Steel Oil Filled Pressure Gauge