1.1 This practice covers the use of magnetic- and eddy-current-type thickness instruments (gages) for nondestructive thickness measurement of a coating on a metal substrate.1.2 More specific uses of these instruments are covered by Practice D 7091 and the following test methods issued by ASTM: Test Methods B 244, B 499, B 530, and G 12.1.3 The values stated in SI units are to be regarded as standard. The inch-pound units in parentheses are for information only and may be approxi