At the time of buying this I doubt whether it would work. But , it works and does everything it says . A professional tone tester is priced around $700 . But this little thing is all you want if you are a small time IT guy like me . It even comes with two 9V batteries .Yes , I recommend this product .
I bought my first toner about 15 years ago and wasn't too happy with it because I couldn't hear the tone in a noisy environment which is very common on construction sites. It was a major brand (Ideal) that I bought from Home Depot and it cost twice as much as this Monoprice unit. This Monoprice unit is far superior to my prior unit.
The Monoprice unit comes in a very nice cordura case which can be carried on your belt. The buzzer is louder than my previous toner but this one comes with a small set of earbuds in case you're in a noisy situation. Another big bonus with this unit is that it also has a flashing LED. So it notifies you both ways: by ear AND by sound.
My only complaint is the instruction booklet doesn't make sense. It's written in another country obviously because it doesn't do English very well. The inferior User Guides seems to be a common customer complaint to Monoprice, So I hope they are listening and will adress this problem with all their products.
This unit still gets 5 stars because I know of no better value anywhere.