The upright and moving seats on the Half Ball does my back extremely well. Back pain that adapt else during prolonged sitting, do not arise - on the contrary: existing back problems are significantly alleviated by sitting on the ball and pass even half! And all that just sitting down! I am excited about this Topstar fitness stool Sitness Half Ball - and I do not sit just like on the stool, but I gather the Half Ball also to use it on other chairs. Sitting on doing my back always good - and is a very comfortable training!