The Technicians kit is Contretron popular field service kit for telephone and security technicians. The RFX-1500/2500 is primarily designed for use outdoors. The RFX-2500 Receiver has been set up with a very hi gain. Using this Receiver indoors is not recommended except in large office tours and industrial sites. This kit allows them to locate all wires and cables inside a building or buried in the back yard.