Ultrasonic Thickness Gauge Kit, Digital DisplayExclusive micro computer LSI circuit and crystal time base offer high accuracy Digital display provides exact readings without guessing or errors Broad band receiving sensitivity means the meter can read probes of different frequencies Automatic material calibration Selectable metric or imperial Measures the thickness of steel, cast iron, aluminum, red copper, zinc, quartz glass, polyethylene, PVC, grey cast iron and nodular cast iron Display sound