I purchased this power wrist ball spinner by #TimeSport as a way to strengthen my wrist and forearm after having it broken years ago and only regaining limited strength. After a few uses I've noticed a very noticable improvement on movement and strength. I'd highly recommend this as a part of one's rehabilitation after a sprain or break of the forearm and or wrist. At only $16.99 this is a very small price to pay in order to gain a lifetime of strength to one's wrist and / or forearm.