It is said that Hippocrates treated patients over 2000 years ago using a heavy animalskin ball filled with sand. In two millennia, much has changed, but the efficacy of benefit of medicine balls has not. An explosive and kinetic alternative to traditional weights, you can perform hundreds of exercises that work every area of your body and improve flexibility, coordination, and movement. Add a medicine ball to supercharge basic calisthenics, or try rebounding for an active, exciting way to work your arms and core. We've gone ahead and ditched the animalskin and sand in favor of tuff, grippy rubber inflated with air. Not only does air offer completely customizable firmness, but it works in tandem with the durable rubber to produce significant bounce when rebounding--much more than sand or gel-filled balls. In addition, the rubber exterior is covered with hundreds of dimples, like a basketball, so you can maintain a secure grip, even in the middle of an intense workout When choosing your weight, pick a ball that is heavy enough to slow your motion, but not so heavy that control, range of motion and form suffer.Choose a weight that's heavy enough to slow your motion, but not so heavy that control, range of motion and form suffer. Rubber exterior is covered with hundreds of dimples so you can maintain a secure grip, even in the middle of an intense workout. Crafted from tough, durable rubber and inflated with air. Add or remove air to achieve your desired level of firmness. Great for rebounding and other bounce exercises, unlike sand or gel-filled balls. Add a medicine ball to supercharge basic calisthenics, or try rebounding for an active, exciting way to work your arms and core. An explosive and kinetic alternative to traditional weights. Perform hundreds of exercises that work every area of your body and improve flexibility, coordination, and movement.Sport Type: Basketball. Item Weight: 4 Pounds. Color: Blue, Black. Material: Rubber. Brand: Crown Sporting Goods. Date First Available: September 8, 2015. Best Sellers Rank: #53,476 in Sports & Outdoors. Customer Reviews: 4.6 out of 5 stars 151 ratings 4.6 out of 5 stars. : B0153VK0D2. Sport Type: ?Basketball. Size: ?4 lb. Part Number: ?SMBL-001. Manufacturer: ?Crown Sporting Goods. Material: ?Rubber. Color: ?Blue, Black. Brand Name: ?Crown Sporting Goods. Item Weight: ?4 Pounds. Package Weight: ?1.81 Kilograms. Item Package Dimensions L x W x H: ?7 x 7 x 7 inches.