This stainless steel thermowell is 3" long, and fits into a 7/8" hole that you drill. Features two flat silicone sealing washers for both sides of the pot. and large stainless sealing surfaces for the washers to prevent leaks. Features an exclusive silicone rubber cord stop and holder, so you can install a probe and wire. Fits all 1/4" diameter Johnson Controls and Ranco digital temperature probes (does not fit the probe on our E26 Controller). The interior diameter of the 3" thermowell is .285"