Total Measuring Range (depends on material and transducer/probe type): 0.025 - 36.000 inches (0.63 - 914.4 mm) Measuring Range on Steel (with standard T-102-2000 probe): 0.040 - 8.00 inches (0.60 - 199.9 mm) The Dakota ZX-2 fixed-velocity ultrasonic thickness gauge is a basic fixed-velocity gauge that requires no special training to operate. Calibration is done by simply scrolling to a known material velocity, or selecting a common material from a list of material types.