The Kamagon Ball is a unique core stability product that bridges a necessary gap in the functional training market. It can be filled with water to create variable shifting loads. This unique ball uses hydro inertia; that recruits a greater number of muscle fibres when performing the most basic to advanced exercises. Diameter 36cm. Kamagon Ball is used for full body workouts engaging in full range of motion exercises. Water lines imprinted on the ball allow for accurate water measurement. Holds up to 45lbs (20kg) of water.