The Murphy 130-250F Temperature Swichgage 2.5" with 40 Ft Capillary A25T-250-40-1/2 is a diaphragm-actuated, temperature-indicating gage with built-in electrical switch for tripping alarms and/or shutdown devices. This rugged, built-to-last instrument is fully sealed from the environment by the unique combination of a polycarbonate case and lens, a polished stainless steel bezel, and O-ring seals. This vapor/pressure actuated gauge features a sealed capillary tube and a sensing bulb. When subjected to heat, the liquid in the sensing bulb changes to vapor creating pressure against a diaphragm mechanism. The diaphragm translates this vapor pressure into a mechanical gage reading.