I would recommend instead using the XSF ITTF approved ball. It is rounder, has a bounce more like celluloid, and has much better playing properties. It is still slower and less spinny but the bounce is more predictable and it messes up your timing less than the others. I have spent a lot of time in the last two months with 40+ balls. I have tried Joola, DHS, DF, several versions of XSF, Nittaku SHA, and most recently TSP (which I have heard is made by DF). My conclusion is that the Chinese seamed balls are still pretty bad (mainly because of deviations from roundness, fragility, and very low bounce). I have also based my conclusions on comments from three former US team members who play at my club and who try these balls as I received them. The earlier versions of XSF seamless balls were really awful, so I was very skeptical about the whole concept of seamless balls, but the latest ITTF version is not the same as what they were producing a few months back. In North America they are sold by Pingpoing Depot, a Canadian company (used to be Table Tennis Pioneers). I don't sell balls or equipment (unlike at least one commenter on this thread), have no commercial interest in any TT company or manufacturing process, and have no connection to Pingpong Depot. So this is an unbiased review.