There was a lot of traffic about these training devices a while back and I am wondering if the people who purchased them are still using them and still finding them useful. Personally, I used the wonder wedge for about six months, I found it really improved my awareness of my grips, but in the end I couldn't produce enough juice on my serve with it on my racket (though I got great amounts of spin.) I think the product helped my game a lot, but it did not prove to be something that I wanted to keep attached to my racket forever. I am curious to hear other people's experience with this, and especially the A.P. belt.