Temperature: 130-250� F. Fits Standard 2-1/16″ Opening. Diaphragm-actuated, temperature-indicating gages, with built-in electrical switches for tripping alarms and/or shutdown devices. These vapor actuated gages feature a sealed capillary tube and a sensing bulb. When subjected to heat, the liquid in the sensing bulb changes to vapor creating pressure against the diaphragm mechanism. The diaphragm translates this vapor pressure into a mechanical gage reading. The gage pointer acts as a temperature indicator and as one switch pole which completes a circuit when it touches the adjustable limit contact. Contact(s) are grounded through the Swichgage case. Dial: Black with white markings. Case: Plated steel with polycarbonate, high-impact lens. Bezel: Polished stainless steel. 1/2″ N.P.T.