Locate the correct circuit from the box every time with the Breaker Finder XR from GTi Products. This is an indispensible tool for anyone who needs to verify and pinpoint live circuitry from the breaker box - even for fuses and GFCI circuits! A blinking LED and audible tone from the receiver unit makes it easy to locate the circuit in which the transmitter is plugged. Works on single and polyphase circuits that operate on 90 to 600 volts.