304 stainless steel case bottom brass connection oil composing: ... 2",2.5",3",4",6". Bottom Brass Connection Stainless Steel Oil Filled Pressure Gauge 1. Diameter: 1 ½", 2", 2 ½ ", ... 3",4",6";2.Case: 304 stainless steel;3.Window:polycarbonate;4.Internal: brass, stainless steel ... 5%,1.6%,1%. Bottom Brass Connection Stainless Steel Oil Filled Pressure Gauge