The Forcefield Fence Test Beeper is a device to check if there is power on a fence line. It is very easy to use. Simply hold the beeper beside the line and if there is current the tester will beep. The tester is small and easy to carry, acting as a keyring it has the dual purpose of keeping your keys together. The Forcefield Keyring Fence Tester is a must have for anyone working with electric fences