If you work with high-temperature thermocouples and youd rather test them than throw them out, but you haven't found a calibration instrument that checks them economically, now you have a solution. This calibrator delivers all the benefits to make verifying your thermocouples productive and effective. Insert B (comparison block) 2Ea 3/8, 2Ea 1/4, and 2Ea 3/16 holes.