Cheap And Discounts NDT block 1018 Steel Calibration Block for thickness gauge ASTM E797 5 step 0.1"0.2"0.3"0.4"0.5" Wholesale. Buy Directly From Merchant LANYU INSTRUMENTS STORE. Enjoy ✓Free Shipping Worldwide! ✓90 Days Buyer Protection. ✓Easy Return. ✓Money Back Guarantee.