FEATURES Cutting Edge: The BOSU(R) Surge (R) 40 is a training device focused on health, fitness, and performance improvements Visual Feedback: The Surge(R) 40 is clear which allows you to see the water crashing and shifting inside, giving you the opportunity to make adjustments and aid in programming on the fly Muscle & Joint Improvements: The Surge(R) 40 is designed to challenge your joints and assist in muscle stabilization. Changing Conditions: The shifting of water in the Surge(R) 40 urges your body to fight against the changing conditions resulting in enhanced stabilization Versatility: Farmer's carriers, overhead lunges, and many other workouts are perfect for the Surge(R) 40. Train your body to react to real life movements and changes rather than static movements used in traditional workouts. Core Training: The Surge(R) 40 offers more than 50 customized movement patterns that mimic real-life instability giving you a one-of-a-kind workout SPECS Weight: Choose your desired weight depending on the amount of water you add or remove; when fully filled the Surge(R) 40 weighs 40 lbs. Grip Options: Three (3) grip options allow for versatility in workout and fitness trainings