Pressuretrol Controller, 20-300 PSI Operating Pressure Range, 20-50 PSI Differential Pressure, SPDT Snap Action, Make R-W, Break RB on Pressure Rise, For Use with Steam, Air, Noncombustible Gases or Non Corrosive Fluids, 120Vac/240Vac, Mount using 1/4"NPT Internal Pipe Threads or Surface Mount Through Base of Glass