The Hubbell P65 Replacement Probe-Sensor is a accurate temperature monitoring partfor heating systems. The essential component includes a 1/4" x 2-3/4" probe with an O-ring alongside a 22" cable which has a computer plug to enable easy integration into current systems. This sensor operates reliably without a metal thermowell yet the "P65 WELL" model is available for complete assembly ... https://partsfe.com/p65-hubbell-replacement-probe-sensor