The reason why I gave it 4 stars becasue I really am short and I wish they have offer different sizes for the ball (I could have gotten kid one). I tried to deflate the ball so I can sit but it doesn't feel right - it's best when it's fully inflated. So it's a little too big for me (i'm only 4'11) So if you are a short person, you have to keep that in mind- perhaps you can go for a kid chair which will fit you better than the adult size chair. But it is really good chair. It helps my back.
I've had the chair for a month and I love it. It allows me to actively stretch, have mobility, and strengthen my abdominals while sitting and working on the computer. Not only that but because the chair facilitates mobility even while sitting, I don't get as frozen in place from concentration in the same way, and I get up to move my body much more often. The chair helps significantly to counteract the accumulated damage from sitting for long periods.
The chair is easy to put together and a pump is provided with the package, so the ball takes no time to blow up. I have been very pleased with the chair- very comfortable and I am not as tempted to slouch at my desk. Highly recommend!
Love, love, love having the chair. Unfortunately the ball does not hold air very long. A co worker of mine purchased the same chair about 3 months ago and the ball she has is definitely a better quality, more substantial, thicker feeling. Hers is still as full of air as the first time she filled it up. I had to get a replacement ball already. The second one seems to be doing the same thing, slowly looses air. I'll deal with it because I like sitting on the chair.
Bought it a few weeks ago and I alternate between sitting in a regular task chair and I can already feel the difference. Most days, I go the entire day on the ball without realizing it. Love, love, LOVE it!