I've got the Triplet Jr set. http://www.amazon.com/Triplett-3375-.../dp/B002FY00B8
Works for me. I was able to trace a 110 volt wire (disconnected from the breaker box) down the wall from the breaker box and then below the floor of my motor home to a point that it turned and went under my couch. I was looking for a receptacle box that was not being used but had wiring from the breaker box to the receptacle. The Fox & Hound helped me find the receptacle in an enclosed compartment in my basement. I don't think I would have found the receptacle any other way.
This set has a headphone jack and you may need to use a headphone to hear the tone as you trace the wire. I did with that 110 volt wire but with some others I didn't need the headphone.