The 3100 Series consists of a single pole, single throw switch activated by a snap-action bimetal disc. Temperature calibrations are pre-set at the factory and each unit is 100% thermally and mechanically inspected. It is available to open or close on temperature rise. The case is laser welded to form a hermetically-sealed steel housing with a glass-to-metal seal at the terminal junction. It is manufactured and tested to meet or exceed critical commercial and industrial specifications. .. see full description