... Pressure Gauge 1. Diameter: 1 ½", 2", 2 ½ ",3",4",6";2.Case: black steel case;3.Window:glass, acrylic, polycarbonate;4.Internal: brass, stainless ... /8", 1/4", 3/8",1/2",NPT,BSPT,BSP;6.Connection: bottom connection, center back male connection;7.Range:0 ... .Oil composing:glyceine, silicone oil;10.Accuracy: 2.5%,1.6%,1%. Black Steel Case Dual Scale Dry Pressure Gauge