The Eaton MCS4 presostat is an electronic pressure switch module with an SPDT (Single-Pole Double-Throw) switch output. It is used to detect and control vapor pressure in closed cylinders and fuel tanks. The module is set to a desired pressure range, and once reached, it will switch the output. This allows users to adjust and monitor pressure levels. The MCS series is designed for use in harsh industrial applications, and guarantees reliable operation in a wide variety of environments.