I used one of these at my last job. This is a wonderful chair. The first time that I sat on it I fell off, but then once I learned how to sit on it, it was amazing. It kept my back straight, and kept me sitting upright, and I didn't feel so sleepy after 8 hours at the computer. I love this chair. It it worth the price. 5 stars

It seems comfortable for short sessions; however, when I sit on it for 30+ minutes, I find a hard time walking due to lower back pain. If you suffer from posture problems that affect shoulers and neck, I recommend it; if you have lower back problems, I don't. 3 stars

I've been using just a plain gym ball as a chair instead. You don't really need or miss the back because the ball gets you to hold your spine in correct allignment. So I recommend just buying a ball (much cheaper) and using that alone. 3 stars

I purchased this Gaiam Balance Ball Chair in late December 2005.

It's an item you have to get used to if you've sat in regular office chairs for a long time (I've sat in padded-foam/plastic chairs for over 15 years, over 40 hours per week). I'm 6 feet tall, 155 lb., and practice Vinyasa Yoga every now-and-then, and I am no Yoga expert by any means.

1. The purpose of doing Yoga ball exercise is to align your body through training the core muscle in your torso--your abdominal muscle will help support your back. This practice, over time, will give you better posture. Also, "constant-centering" myself on the ball reminds me not to bend forward my shoulders or slouch.

2. My old office chair has a pneumatic height adjustment at 19"-20" This ball seat height (with the doughnut-shape base) is about 23" tall; sitting down on it, at my weight, brings it down to about 18"--of course, it will depend on your monitor/keyboard setup and on how much air you put in the ball. I raised the table height 3" higher and purchased an adjustable keyboard/mouse extension tray. I make the ball as firm as possible.

3. The back support is detachable (which I've done) and allows you to center yourself over it more. Don't lean on the back support for too long, or you may hurt your lower back.

4. You will experience some back pain for a few days, some shoulder pain if you're use to having an armrest, and neck pain if you had a headrest. Keeping my chest open and head up help my abs stay taut.

Minus half-star for the rolling wheels because they sometimes trip me over when I get up and stand. So, I spread my feet and use my leg muscles to stand upright. I recommend it still because it motivates me to get up and walk around. It's not healthy to allow the legs be pooled with blood (which causes veining) over two-three hours at a time. This item is at a decent price range, offered here on Amazon. Hope this helps! 4 stars

I love my ball chair and sit on it continuously at work. It was easy to get used to and I can move around quickly and easily. My sitting posture has improved.

I do have one complaint. My pants were showing a lot of wear and tear in their bottoms. After sitting on a pillowcase on the ball for a while proved that the material the ball was made of was the source of the problem, My seamstress mother made a fabric cover for it and...no more problems! 4 stars