Zenport Zen-Tek Instruments ammonia filled 0-160 psi pressure gauge is designed to measure pressures in systems charged with NH3 Ammonia. Constructed with a 2.5-inch diameter stainless steel case and bezel, PC window and stainless steel 1/4 National Pipe Thread bottom connection the internal components and connections are all stainless steel and will not corrode. This quality gauge features grade A accuracy (1.6%) and features a high visibility dial and number readout.