This Klixon? snap–acting disc type control is designed to provide crisp, positive switching action. The 4391 is the most versatile of the Klixon? precision thermostats with its available SPST or SPDT switching, automatic or manual reset, and overmold options. The high current carrying capacity in a hermetic package make it ideal for applications such as aircraft galley equipment, aircraft lavatory hot water heaters, semiconductor equipment, and locomotive/railcar heaters.