Built to be punished, the TWL Slam Balls have a thick, high strength plastic barrier to prevent against splitting even when taking the strongest of punishment. - The no bounce design means you will be getting the full benefit from the Slam Ball during the workout. - A solid Slam Ball workout will increase your strength, endurance and core. - Available in a number of weights, there will be the perfect Slam Ball for you in our collection. - Features: Zero Bounce Textured grippy surface for easy grip Filled with sand Perfect for indoor or outdoor Build Strength & Endurance Variety of Sizes Available To increase longevity of Slam Ball, never use on concrete or bitumen surfaces. - Specifications: 3KG – 9KG: 9in diameter 10KG – 20KG: 10in diameter PVC surface and sand filled