I have one. Unfortunately, it is now in a corner, gathering dust. When I first sat on one at the LQS, I thought it was very comfie and I hoped that it would help with the backache that I get after being at my machine for too long. I don't think I noticed any difference and after I moved it once, I didn't bother to put it back on my chair): Seemed like such a good idea at the time. Maybe it will work for you, though.