Elcometer T456CF6S Straight Ferrous Substrate Probe, Scale 6, Range: F - 0-980 mils (0-25mm) / N - 0-1200 mils (0-30mm). Measures coatings on both flat and curved surfaces. Ferrous probes measure non magnetic coatings on ferro-magnetic substrates Elcometer 456 ferrous gauges accept any ferrous probe. Non-ferrous probes measure non conductive coatings on non-ferrous metal substrates and Elcometer 456 non-ferrous gauges accept any non-ferrous probe. Dual FNF probes measure both ferrous and non-ferrous application with automatic substrate detection. Elcometer 456 FNF gauges accept all ferrous, non-ferrous and dual FNF probes.  Elcometer probes have a maximum operating temperature of 80° C (176° F) with the exception of separate ferrous probes 150° C (300° F) and Hi-Temperature PINIP's 250° C (480° F).  The stated temperature is the substrate temperature, and the duty cycle of the probe must be reduced to ensure a minimal temperature build-up within the probe. All Elcometer probes are supplied with a test certificate and a set of calibration foils appropriate to the scale range of the probe.