The 65cm BOSU(R) Ballast(R) 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(R) Ballast(R) Ball provides a fun, visual effect and audible feedback during lifting, shifting, and shaking exercises. With the BOSU(R) Ballast(R) 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. BENEFITS: Tone and strengthen Improve balance Improve flexibility Strengthen core Dynamic functional training SPECS: High-quality, latex-free, burst-resistant material Made in the USA 1 year limited warranty Holds up to 136 kg (300 lbs.) Diameter: Inflate between 55 cm and 65 cm Weight: 2.95 kg (6.5 lbs.) digital owner's manual included Inflation Range: 55-65cm 2.5 lbs. of ballast material inside ball