I've used lots of 40+ balls for trainings and competition, but for me this is the only ball that is really good in QUALITY like good old celluloid balls. If you take other balls box of 6, you can throw off half of them because they're unplayable (not round and soft) at a higher level, like topspin to topspin. These are all perfect round and hard. They are more expensive, but it's worth to pay extra money, because it breaks 2-3x less. For example if you take Xushaofa - it's enough to hit harder one time with corner of the blade to break it. This premium ball will break only after 3-4 corners. Also lots of world top players (Ovtcharov, Boll, Samsonov) said they would like to play all competitions with these balls. I can say the same.