The certified step blocks are used to verify the accuracy of an ultrasonic wall thickness gauge. These blocks have a certificate traceable to NIST to go along with them. They are constructed from 1018 steel, so they maintain their accuracy overtime. The steps are 100, 200, 300, 400, and 500 mils with an accuracy of ±1 mil.
If a wall thickness gauge is needed to go along with the step blocks our full selection can be found here: https://ktagage.com/product-category/wall-thickness-gauges/.