BOSU Ballast Ball - Blue (65cm)

I have used this type and size of ball for many years for situps, as they cushion my tailbone. While I've had other brands, none are as superior as the Bosu ball. For starters, the inflation plug is really easy to extract and to reinsert while retaining the air. The included accordion pump is a bit interesting, in that it makes a high-pitched squeak when stepping on it to do the inflation, so my resident engineer went and got our shop-vac and blew up 95% of the ball that way, and we finished it off with the accordion pump. All in all, for comfort and overall perceived durability, this is great. It might be a bit more pricey than others, but I'm sure it will last magnitudes of measure longer.