With the Sitness Half Ball from Topstar, you get a "2 for 1" product. As a design fitness stool, it can be infinitely adjusted to the desired seat height. The three-dimensional movable seat surface is formed by an air-filled half ball that is encased in a 3D mesh fabric. The cover can be opened with a zipper, allowing the half ball to be used as a training device for the abdomen, legs, and buttocks. After training, you simply place the ball back into the cover to restore it to a stool. A pump for inflating the half ball is included in the delivery. As a stool, the Sitness Half Ball also features a stable, aluminum-silver painted base with wheels designed for carpeted floors. It has been tested by Intertek Fürth and bears the GS mark, which certifies that it meets all safety-related requirements.