The A75 gauge has been developed for pressure measurement of ammonia compressors. The gauge has a stainless steel housing and is filled with glycerine for reliable operation and long life. The seal between the plastic window and the housing prevents leakage by means of a bayonet catch with sealing ring. A connection nipple is fixed to the housing in a unique way making external connection screws unnecessary. This gives extra protection against leakage caused by vibration.