Used for measuring thickness and corrosion of pressure vessels, chemical equipment, boilers, oil storage tanks, etc.In industries of petroleum, shipbuilding, power station, and machine manufacturing. Model: tm8812 tm8812c Measuring range (metric/imperial): 1.0-200mm, 0.05-8inch Operating principle: ultrosonic Materials measured: any hard materials, including steel, cast iron, aluminum, red copper, brass, zinc, quartz glass, polyethylene, pvc, gray cast iron, nodular cast iron and other materials Sound velocity: 500-9000m/s Lower limit steel pipes: 15x2.0mm, 20x3.0mm determined by the transducer Calibration block: included Resolution: 0.1mm(tm8812c 0.01mm) Accuracy: (0.5%n+0.1) Rs232c interface: with rs232c Power supply: 4x1.5v aaa (um-4)battery Battery indicator: low battery indicator Operating conditions:0-+45(32-104), 90%rh Dimensions: 120x62x30mm Weight: 164g(not including battery) Optional accessories: 6m6mm thin material probe:measuring range(steel): 1.0 50.0mm operating temperature: -10~+60 5m12high temperature probe: measuring range(steel): 1.0~225.0mm(normal temperature) measuring range(steel): 4.0~100.0mm (high temperature) operating temperature: -10~+300.