I play singles 3 to 6 times per week with a partner, and we picked up a bag of Wilson "No Nick Name" practice balls a couple of months agos and found that these balls will out last regular balls that we have played with many times over. I can take an old practice ball, and test drop it with a brand new Champion, Penn or Dunlop, and it will match and sometimes even exceed the bounce height. The only thing I have noticed is recently I have started playing doubles with a group that plays with normal canned balls (Wilson, Dunlaps, etc.) and for the first few games I tend to hit the ball long with my groundstroke. But then settle in and my normal fairly good groundstroke starts dropping in. I think it has to do with playing under pressure that I am not used to and failing to keep my eye on the ball and not because I am hitting a different kind of ball. But I could be wrong. Does anyone who has tried them, or has some other knowledge of the Wilson practice balls have an opinion? Is there any reason we should not be playing as much as we do with them? They come in a mesh bag at WalMart. Thanks!