Vktech&reg; 1/8" NPT Air Compressor Hydraulic Pressure Gauge 0-60 PSI Back Mount 1.5" Face This gauge has 1/8" NPT male threads which come out the back of the gauge. This gauge is a top quality gauge made with a black steel case and a chrome front bezel. This gauge has number markings at 0,10,20,30,40,50,60 psi. 1.5" face 1/8" male npt threads, which measure about 3/8" outside diameter.