Utilizing ultrasonic signals the CHM2000 determines the height of overhead cables and wires without contact. It is designed to measure the height of the lowest or highest cable and give the distance between up to six cables. It operates on telephone, power, CATV and street lights. Built into the unit is an air temperature measuring port directly connected to the microprocessor to maintain accuracy at any temperature.Measurements are displayed in feet and inches or meters. The range is from 7' to 35' on cables of 1/4" to 1" in diameter and from 7' to 32' on cables 1/8" in diameter. The resolution is to the nearest 1/4" and the accuracy is typically 0.5%. Operates within specifications at air temperatures between +14° and 113° F. 9V battery included.