DeFelsko S Series Epoxy on Steel Round Metal Plate, 1-1/2" Diameter, +/- 0.017 mil Accuracy, For Thickness Gauges Used to verify the accuracy and operation of any type 1 (mechanical) and type 2 (electronic) magnetic, eddy-current or ultrasonic coating thickness gage Ideal for use in the calibration lab, in the field or on the factory floor Standards with steel substrates Individually serialized for traceability to NIST or PTB, includes a certificate of calibration Certified and labeled in both metric and imperial units