Fueltech 5005100388 CHT Cylinder Head Temperature Thermocouple is a Type-K temperature sensor with a 0.588 in. inside and 0.938 in. outside diameter ring tip that will work with most cylinder head bolts. The ring tip has a lower thermal inertia than standard temperature sensors, giving it the ability to read faster and more accurately. Compatible with FuelTech EGT-8 and ETM-1 Conditioners (sold separately)