I orgianlly ordered the white ball withut realizing that it was meant for people shorter than I am (5' 9"). The Amazon page for it never mentioned that different balls were for different height users. When the ball arrived the sizing was made clear on the box. So I returned it and ordered this ball (Blue, 65CM) which is meant for my height. Having used balls in my health club, but without ever noticing their size, I was surprised at how large 65 cm was. When properly inflated this ball is too large for me; many of the exercises one does with these balls require wrapping the legs around the ball, which is difficult when it is too large. On the Amazon order page for this (blue) ball and the larger (red) ball, the size/height relationship is stated, and I do fall into the range of this 65 cm ball. But it is simply too large--a fact you can't realize until you inflate it. 5 stars

At 5'1", this stability ball is perfect for my height Although the photo shows the ball to be a silvery color, mine is actually a pearly white, which I prefer. Working out with the ball is fun, so it makes it seem much easier. My abs and arms really felt it the next day. 5 stars

Ball was as advertised. Pump a little cumbersome. Pump had a little tear in the tubing that i patched up with tape before I could use it. 3 stars

I am happy with this ball because of the size for my height. I assembled it with no problem. 5 stars

It was hard for me to figure out what size would be right for me but this is pretty much a standard size for anyone. Just make sure you inflate it completely. 4 stars