Pressure switches RD-OM5 and RD-OM5-A (hereinafter referred to as devices) are components of refrigeration units and are designed to monitor, control and regulate the pressure of gaseous and liquid media that are not aggressive to steel (for RD-OM5-A), brass (for RD-OM5) in refrigeration units used on ships, railway and automobile rolling stock and in stationary refrigeration units. The devices RD-1-OM5-01.1 and RD-2-OM5-03.1 are used for the same purposes on crane air conditioners.