... oil diameter:1.5",2",2.5",3",4",6". Bottom Brass Connection Stainless Steel Oil Filled Pressure Gauge 1. Diameter ... /4", 3/8",1/2",NPT,BSPT,BSP;6.Connection: bottom connection, center back male connection;7.Range:0~10,000psi ... :glyceine, silicone oil;10.Accuracy: 2.5%,1.6%,1%. Bottom Brass Connection Stainless Steel Oil Filled Pressure Gauge