My NSD powerball helped my RSI and carpal tunnel syndrome in double quick time. I play guitar a lot and was sick of playing through pain. I do not sell this product, nor am I affiliated to it, this review is written in the spirit of fair play to a product which actually delivered what it promised.
Within a couple of hours use I could tell the powerball was working, I had tried acupuncture, osteopaths and spent hundreds on treatments, I even tried resting for 6 months (if you play guitar you will know this is extreme punishment) but it just didn't help. I would say it took around 2-3 weeks use to regain my full range of motion in my left wrist and now after a couple of months use I can play all day again.
As ever do make sure you avoid knock off products, the genuine item is branded NSD and is available from a few reputable uk ebay sellers.
I edited this review very slightly a few years on as I still have twinges here and there, this is caused by my incessant guitar playing and is, I suppose, to be expected. I also wanted to add that if you're in a lot of discomfort that rest, massage and light work might be a better option. In short if powerball hurts you you're not ready for it. Also I didn't mean to disrespect Osteopaths, part of my problem is I now understand due to a cervical vertabrae and this needs Osteo.