Fluke 140 tone probe detects and amplifies audio tones in the 500- to 5000-Hz range. Because only the probe`s tip detects the signal, technicians can easily find the correct cabling link. The unit also identifies a pair in a 25-pair backbone cable. Battery life of the unit is 40 continuous hours, and the unit automatically powers down after 5 minutes of idle time to increase battery life. List price is $150.