This ball turned out much smaller than anticipated. I previously had an exercise ball, which I thought was the same size, but the old one was much bigger. I used a bike pump to fill it, as it does not come with a pump. It didn't get quite up to a 26 inch diameter. Had I realized how small it was I would have purchased the 30 inch one or maybe even gone up to 34 inches. This ball is around the height of a foot rest. Not round enough for me to get a good, safe back stretch. That said, the bumps are great texture that I personally enjoy and the ball seems to be sturdy and thick. I would recommend, just be aware of the sizing. Reading other reviews on the website, sizing seems to be an issue with other exercise balls as well.