3375 is a Fox and Hound Jr™ compact tone & probe kit traces security, thermostat, data, telephone, audio and other types of wiring. It consists of the Fox Jr Tone Generator and the compact Hound Jr Inductive Amplifier Probe. The Fox Jr is a battery operated handheld multi-function toner that generates a warble tone with a user adjustable pitch. It connects easily with alligator clips or RJ-11 / RJ-45 combo pluga and has 120VAC line cross protection. The Hound Jr is a battery operated handheld lightweight probe, with a thumb-wheel sensitivity control and signal strength indicator LED that can detect trace tones up to 12" away. It has a built-in earphone jack that will automatically mute the loudspeaker for use in quiet or noisy areas.