The Extech CG204 Coating Thickness Tester with Automatic Recognition of Ferrous and Non-Ferrous Substrates is a portable meter designed for noninvasive coating thickness measurements. The tester uses dual technology that provides automatic recognition of ferrous (magnetic induction measurement) and non-ferrous (eddy current measurement) substrates. The CG204 features two measuring modes: Single and Continuous, 400 reading memory storage, and user-programmable high/low alarms.