Ultrasonic Thickness Gauge 4 Digits LCD Digital Display Thickness Measuring Meter 5MHz GM100 Item Type: Ultrasonic Thickness Gauge Display: 4 Digits LCD Display Minimum Display Unit: 0.1mm Operating Frequency: 5MHz Measuring Range: 1.2 to 225.0mm (steel) Minimum Limit Value of Pipe Measurement: 20 x 3mm (steel) Accuracy: ±(1% H+0.1)mm, H represents the measured thickness Sound Speed Range: 1000 to 9999m/s Sound Speed Measurement for Given Thickness:  Measuring Range: 1000 to 9999 m/s When the given thickness exceeds 20 mm, the accuracy is ±1%; When the given thickness is less than 20mm, the accuracy is ±5% Operating Temperature: 0℃ to 40℃ Power Supply: 3 x 1.5V AAA 800mAh alkaline dry battery (included battery) Working Current: Normal working current ≤50mA Reversing Lamp Opening Current: ≤120mA Standby Current: ≤20uAMaterial and Sound Speed (m/s):  Aluminium: 6320, Zinc: 4170, Silver: 3600, Gold: 3240, Tin: 3230, Iron and Steel: 5900, Brass: 4700, Copper: 4700, SUS: 5790, Acrylic Resin: 2730, Water (20℃): 1480, Glycerol: 1920, Water Glass: 2350, Acetate Resin: 2670, Phosphorous Copper: 3530, Rosin: 4430, Glass: 5440, Inconel: 5720, Mg: 6310, Monel Alloy: 6020, Nickel: 5630, Steel 4330 (Low Carbon): 5850, Steel 330: 5660, Ti: 6070, Zirconium: 4650, Nylon: 2620