It goes in many applicances including furnaces and dryers. It will replace all limits rated at 300 degrees with a frame size of 36TX16 (5/8″ insertion diameter and 7/8″ from mounting hole center to center). Look at your limit switch and you should find the temperature rating of yours listed on the switch itself (It will be the first three digits after the “L” number). A limit switch is a safety device designed to shut down a piece of equipment. Limits have a set point, which is in some cases, adjustable. The set point prevents the temperature or pressure from exceeding the rating of the switch. It goes in many applicances including furnaces and dryers. It will replace all limits rated at 300 degrees with a frame size of 36TX16 (5/8″ insertion diameter and 7/8″ from mounting hole center to center). Look at your limit switch and you should find the temperature rating of yours listed on the switch itself (It will be the first three digits after the “L” number).