The G.A.L. Gage Co. Cat # 18 Digital Welding Gauge GAL-18, Inch & Metric is an easy to use tool. This tool Holds either the zero setting or measured val ue at any position for differential measurements, Has a serial output to interface with a computer or printer to process data, Automatically turns on by moving the ma in scale or by pressing ON/OFF key, Automatically turns off after 4 minutes of inactivity .. . conserving battery power.