DuraBall PRO Professional Exercise Ball - Yellow (18 in.)

I purchased this to use with a ball chair and I am very happy with it. This ball is made of thicker material and is more rigid than other balls. When sitting on it for extended periods, the ball does become a little deformed, so I just rotate it every now and then. It doesn't have to be perfectly round for my purposes. I have found that sitting for a long time can become uncomfortable, but I still really like the ball. The thicker material also needs time to expand after first inflating the ball. So follow the instructions. And lastly, this is a relatively small ball...45cm (~ 18 inches). I wanted to sit a little lower to the floor, and as I mentioned I am using it with a ball chair base with wheels, so it works out perfect for me.

The ball is supposed to be for people 5'2" or under, I'm 5'3" one inch should not have been a big deal but it was. The ball is way too small. The quality is great-heavy plastic but way too small.