We offer Pyrometers by Hewitt, ISSPRO, Stewart Warner, and VDO. Pyrometers are used to measure diesel exhaust temperatures, typically at the exhaust manifold. A rise in exhaust temperature is a great early warning sign that a diesel engine is headed for trouble. A pyrometer requires a thermocouple sensor that attaches to the exhaust system to measure diesel exhaust temperature. The thermocouple must be connected to the gauge via a specially designed lead wire (also sold here). Thermocouple must match heat range of pyrometer (HT = High Temperature, LT = Low Temperature). These pyrometer gauges come in both 3 3/8" and 2" inch in diameter. Many of these gauges are lighted, meaning they have a light bulb built in. The bezel is the metal ring around the edge of the gauge, typically black or chrome.