... dry pressure gauge bottom brass connection diameter:1.5",2",2.5",3",4",6". Black Steel Case Dual Scale Dry Pressure Gauge 1 ... . Diameter: 1 ½", 2", 2 ½ ",3",4",6";2 ... brass, stainless steel;5.Inlet thread:1/8", 1/4", 3/8",1/2",NPT,BSPT,BSP;6.Connection: ... , silicone oil;10.Accuracy: 2.5%,1.6%,1%. Black Steel Case Dual Scale Dry Pressure Gauge