Certified Coated Metal Plates and Polystyrene Blocks 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 or aluminum substrates consist of 4 plates mounted in a protective binder Polystyrene thickness standards consist of 4 blocks supplied in a rugged acrylic storage box Individually serialized for traceability to NIST or PTB - includes a Certificate of Calibration Certified and labeled in both Metric and Imperial units