Traces concealed wiring, locates junction boxes, and finds breakers for live or dead circuits-no need for power interruption. Finds breaks in wires and shorts to ground. Incorporates auto gain circuitry for enhanced accuracy. Locates and identifies blown fuses. Supports transmitter-to-receiver distances up to 4 miles (6.5 km) for closed circuit tracing. Accessories included: Adapter lead, (2) 9V batteries, AC blades, instruction video, extension leads, carrying case, earphone/tube. Specifications Capacity: 0 to 600V AC/DC Auto Off: Transmitter 30 min.; Receiver, selectable Case Size: 14" x 12" x 4" (355 mm x 305 mm x 102 mm) Weight: 3.56 lbs. (1618 g) Distance: 3000 ft. to 4 mi. (varies with application)