This adaption of the River Stone features a soft base and a hard top platform supported by three strong steel springs to enable bouncing, which requires adjustment through the child's ankles and legs, making it a more challenging activity than simply stepping. The Bouncing River Stone can be used on its own for special motor training activities, or together with River Stones to provide even more play possibilities. Set includes 1 Bouncing River Stone and 4 River Stones. Bouncing River Stone measures 14.17" x 14.57" x 3.94" . Weight Capacity: 110.25lb.