It does exactly what they claim it will do, and it's a solid, good quality tool. Everything works fine, and it adjusts to a very large diameter.

Now, I'm not using this on a $2500 Baume & Mercier -- I'm using it on Timex and Swiss Army, but I wouldn't be cracking off the back of a B & M myself, anyway. I'll save that job for the pros.

Also, this wrench is inexpensive. Change out one battery yourself, and you've nearly broken even already.