https://www.mikrometry.com/the-difference-between-the-principle-of-magnetic-measurement-and-the-principle-of-eddy-current-measurement-of-coating-thickness-meter.html The coating thickness meter is an instrument used for non-destructive measurement of the thickness of the coating on the surface of metal substrates or non-metal substrates. Commonly there are high-precision coating thickness meters for magnetic and eddy current thickness measurement. The coating thickness meter of magnetic thickness measurement eddy current thickness measurement is also called iron-aluminium dual-purpose coating thickness meter.