I bought a Tennis trainer few days back (i.e. a weight block having a ball attached through a stretchable string). First day it was really worst to play with that and i was really upset with buying it. Though I tried to leave a comment the first day about my experience but I wasn't a member over here. By the time I got membership, I tried that trainer more and now I realized that it takes time to get adjust to it. Now I really like that trainer as this is helping me in adjusting my timing and style. The only problem with this trainer is that if I hit the ball with full power than block moves a single centimeter, so if I continuously play 15-20 hits then I have to get the block back to the baseline. But still it is very good and cheap.