A thermocouple is a device consisting of two different conductors (usually metal alloys) that produce a voltage proportional to a temperature difference between either end of the pair of conductors. Grounded type is more sensitive to temperature, can help to measure temperature fasterly. 5 x 50mm sensor PT100 type Thermocouple with flexible spring built in. 3 terminals for easy connection. Temperature measurement range is from 0 celsius to 400 celsius degree. Widely used for industrial or laboratory to test equipments temperature.