There is no ability to adjust arm support height or knee/floor height other than to deflate the ball so much it loses its purpose. The fact that the ball definately forces you to engage your core muscles is what keeps the rating @ a 3. I don't believe I'd recommend this chair based on the lack of real ability to adjust for different body dimensions.

I initially heard about this chair after speaking to my doctor about my knee problems. I am disabled and at times i find it hard to do anything to ease my pain, other than pain pills. I purchased a recumbent bike and at my doctors request and I also purchased this chair. I would not advise its use to the average healthy user seeking a comfortable chair, but if you are suffering from knee injuries I would highly advise you to try this chair. All though it isn't comfortable to sit in for 3+ hours it is comfortable to sit in for short periods of time and most importantly it helps properly position your knees. I would often sit with my knees in odd positions, because my height and most chairs I sit in would extend my feet forward. My doctor informed me that my poor posture and particularly my knee position, in relation to my feet, while I sit add to my pain. Since I purchased my Cando Ball Office Chair. I have enjoyed the reduced pain periods and find myself needing less pain pills. If you have knee problems I would highly recommend this product.

This is the chair I've needed for a long time. Having Fibromyalgia, I could only sit at my computer for a short time. Using the CANDO BALL CHAIR has allowed me to sit anywhere from 2-4 hours at a time, withouf suffering back or neck pain. I like this chair over other ball chairs because of the back support and the arms. This allows me to change positions easily. I would highly recommend this chair for anyone needing to spend long periods of time at a desk or computer...for me, it beats all other chairs I have tried.

This is an amazing chair. I have a bad back and MS, so it hard to sit for very long in a chair. This is just the right height for me, I am short. You can inflate or deflate the ball according to the firmness you want. I find this a good fit for me. It supports me back, while working on my balance. It is light weight and easy to move.

This is so comfortable and you can tell the difference if you switch back to old chair. My posture is better and my back does not hurt while using the ball chair. Our office has had the chairs now almost two years.

I had purchased just a ball but could not get one large enough as I was looking to use it as a desk ball. I found this chair and thought why not??? It was not too difficult to put together. It's lightweight. I am not sure I am crazy about the arms other than using it for getting up and down but the back support is awesome. Reasonably priced too.

Perfect if you sitting at an office all day. Highly recommend

After several months of lower back pain, I learned through visits with various specialists that I just had weak muscles in my core. After one week on the ball chair, I'm already feeling like me again! I've also noticed my posture is better overall - even in seating where people typically slump.

Got this because of back problems. At first everybody was giving me the funny look at the office. With time lots of improvement on my posture and core strength increase.

Nothing like it out there. This is perfect for the office and will really help your posture. I have back issues and this has helped tremendously. I don't know how I would sit at the computer anymore without it.

I have lower back problems and bulging discs at the base of my spine. That combined with poor posture at my desk left me in a lot of pain often. This chair has really helped promote better posture for me.

1 screw did not line up and the guy who put it together wanted to throw it away, the screw (not the chair). I sit in it all day long, and would like to take the arms off, but then it would look less like an "office chair" and my business is very conscious of this atmosphere. I used to sit on just a ball, and felt more freedom and core strenghtening. The chair is a decent substitute, but I'd rather be on a ball. Hope this helps. I also, went with this chair as opposed to the generic thinking it would be more structurally sound, and unfortunately I think it is within the same grade. Personally, I would rather have a different heavier model.

Love this chair. Keeps my posture straight and no neck pain!

I really like the sturdy metal frame, it is a very sturdy ball chair. However, the armrest is really NOT an armrest, they are too low and if you remove them you'll have metal pieces jutting out.

This chair has made my workday much more comfortable. Thank you!! Plus it's just really fun to sit in ;-)

I may order another of these for home. I sat in the entire day the first day, and didn't notice until I was headed home that my glutes ached a little. The handles are useful for getting up and down but not for resting my arms while I sit. It was not difficult to put together although the directions left a lot to be desired, I few additional instructions would have saved me some time. Rolls very well on the hard floor.

I like this chair as a second chair in my office. It makes you sit up tall. If I were to order another one I would not get the arms or the back. I like the rollers on it. This was my second chair that Overstock sent me because the first one didn't have all the parts. I'm happy with it. It was easy to put together. Overstock was very good about sending me the missing parts and a completely new chair in the box.

The chair is amazing. It is comfortable to sit in. It moves nicely and its fun to bounce around on when playing music.

I purchased 2 of these chairs and they both have similar issues. It is nice to have the back rest but do not really use the arm rests. the connection from the frame to the base tends to get wobbly and need tightening often. The one I use in my classroom is also very squeaky. For a ball office chair I would purchase again as it was not extremely expensive and serves it's purpose.

Love this chair, I use it daily... can only sit a couple hours at a time, but I figured that was going to be the deal going in... it has helped my back quite a bit since I started using it.