HYDRO-USA Pressure gauges are all stainless steel industrial gauge (case, mechanism, tube and process connection) with glycerine filled for high pressure and precision measurement, Psi scale 500 Psi, 30,000 Psi up to 60000 Psi, can be used in chemical processing, instrumentation controls, oil fields, paper plants, agricultural plants, water and waste water Cases are 4″ stainless steel, 1/4″ NPT, 1/4″ MP & 1/4″ HP-9/16-18 UNF connection, lens tempered glass, engineering in USA / Manufacturing in India