Hyperwear SteelBell Steel Shot-Filled Ultra-durable Neoprene Free Weight Slam Ball Extremely durable extra thick neoprene, high quality design, textured for extra grip Patented design takes punishment and works grip, wrist, forearms Shifting steel provides challenging, effective active live weight squat, press, lunge, swing, slam, and wall ball exercises Multiple sizes available easy to stack to store A favorite of elite athletes and still safe for all ages, fitness levels, and floors