The 65cm BOSU® Ballast® Ball is like no other ball in the gym. This ball has a six-sided surface design for proper alignment and positioning. It also has 1.5 lbs. of multi-dimensional load (ballast) which keeps it from wandering during your workout. The BOSU® Ballast® Ball provides a fun, visual effect and audible feedback during lifting, shifting, and shaking exercises. With the BOSU® Ballast® Ball, individuals can perform exercise progressions and dynamic drills that are not possible on a regular exercise ball. Use it like an exercise ball or slam ball.