... ball , balance half ball , half exercise ball, half gym ball , half exercise ball , half bosu ball dia:58cm- ... device, invented in 1999 by David Weck, consisting of an inflated rubber hemisphere attached to a rigid platform. ... the device remains stable. This combination of stable/unstable allows a wide range of users, from the young, elderly, ... better . BOSU balls, half bosu ball, half exercise ball,