Megger CHM2000 Cable Height Meter, 6-Line Separation, 35' Maximum Range Measures the height of up to six overhead cables without touching or connecting to the wires Built-in temperature sensor improves measurement accuracy by accounting for variations in the speed that sound travels in different ambient temperatures Provides readings in meters, feet, or inches Calibration feature helps ensure accuracy of readings Automatically turns off after three minutes of non-use to conserve battery life