[See update at bottom; I learned a bit more after I wrote the first part of the review, with improved results] First let me say that I've used one of the older circuit finders that I got about 15 years ago. This was the kind with a sensitivity knob that you can adjust. I decided to buy a new one because I liked a lot of what I saw in this design. (and also because I couldn't find my old one...) This model has a lot of things going for it: * Nice design that allows both pieces to be plugged together so it's easy to carry in a pouch or toolbox. * Magnetic mounts on the main unit allow it to snap right onto the breaker panel * Sender unit does double-duty as a circuit tester to confirm good ground/neutral/hot wiring, plus, a GFCI test button. This in itself is a great thing everybody should have -- you'd probably pay about $10 for something like separately. Since you'd normally have this in your electrical tool kit anyway, it seemed like a great idea to combine this function into the sender unit. All this is great, but.. as a circuit finder I couldn't make this work well. The problem was also noted by another reviewer: the detector is TOO SENSITIVE and doesn't have any way to adjust this. It has a bar graph indicator and beeper, which would be great to help you localize the target breaker. The problem is that this system gives me a maxed-out reading over almost all my breakers! I understand that these things are hard to use and it takes some fiddling to get used to it (see other Amazon reviews for every other breaker finder for clear evidence of this.) My old one with the manual adjustment was difficult to figure out -- at first, you're just glad to find the signal. Then as you try to localize the breaker, you gradually turn down the knob to reduce the sensitivity. Eventually you get it to the point where you are in the right sensitivity to focus on exactly the right breaker. Yes, it does help if you can remove the metal panel over the breakers -- this isn't always essential but it does help. The problem with this model is that the bar graph indicator just zips right up to the max reading when I am within about 6" of the circuit in question. Since you don't have any way to turn down the sensitivity, all you can do is hold the "wand" further away, but that defeats the purpose of being able to focus in on the target you are trying to find. In my opinion this makes this very nice-looking tool pretty-much useless, except for the nice sender unit which doubles as a circuit tester. I would say I understand the limits of how these work and the ONLY way to really be sure you find the right circuit is to turn off the breaker, and if you get the right one, the signal will stop (because you've cut off the power to the sender). That is the way these work. The best you can hope is that you get "close" to the breaker in question. It still might take a few tries. I could do that with my old model by tweaking the sensitivity. But with this model it seems I'm going to have to turn off every breaker until I find it -- which kind-of defeats the whole elegant purpose of this model to begin with. This is the first day I got it and I was so excited to try it, but unfortunately I'm at a loss unless I can figure out that I'm doing something wrong. I will give it some more tries over the next few days and update the review if I learn anything new. [UPDATE 2 days later] I have revised my rating from a "2" to a "4." I tried it again and learned a few more things about it. It seems that with some learning and effort, this is a pretty good tool. (As I noted in my comments above, ALL breaker finders are difficult to learn to use correctly -- this one just works a bit differently and so there are new "tricks" to using this particular model). Here is what I learned: As you get a strong signal, the bar graph goes up and the tone (kind of a noisy high-pitched tone) gets louder. The key info is that the sender sends a tone, but it has a "beep beep beep" sound mixed in with the other noise. Most of all, I found that there were other things in my house that were sending it a signal that got it confused. I found that over several different parts of my breaker panel, I got a the noise tone and the bar graph went up. However, in ONE of those locations, I could hear a faint "beep beep beep" sound mixed in with the other noise. In the other parts that gave me a signal, I did not hear the "repeating beep." So the key to using this is to listen carefully for the repeating beep sound. And of course, when you isolate the breaker you think it is, turn it off, and that tone should stop. That means you found the right breaker. In my case, other things in my house (I don't know what, but like many houses, I have many little electronic devices) sent it a signal that also gave it a "false reasding." The key is that those tones didn't have the "beep beep beep" component. [Space history fans might think of this kind-of like listening for Sputnik] I would say if you are using this in new construction (i.e. after wiring a new house that is still vacant), this unit would probably work much better because there be no other electrical devices to give it false signals. You also have to be very careful about how you orient the wand and move it over the breakers, and what part of the breaker you move it over. (i.e. the center by the lever, or to the left, or to the right, etc.) Of course there are many kinds of breakers so this will vary based on your equipment, and you have to experiment to find what works best. I would note that I have an older style of breaker (often called "Zinsco") that are very close together (each lever is about 1/4" -- that's pretty small.) Many newer panels use breakers with larger spacing and that might make it easier for some people. Anyway now that I've figured out these three rules, I'm much happier with the unit, and have moved the rating to a "4" * The sender tone has a "beep beep beep" element, though it can be hard to distinguish from the background noise. * Other things in your house might give it a false reading, but if you listen carefully, the false tones will NOT have the "beep" component. * It's very important how you hold the sensor wand, and you have to experiment with this based on your type of breaker. (This last rule is well-documented in the instructions, but the first two items I had to learn the "hard way.")