Sturdy Rubber Construction This Medicine Ball is made from sturdy rubber that is heavy and gives you a firm grip. Textured Surface for Superior Grip The pebbled surface all over this Nivia Ball helps you get a good hold of it while performing exercises. Develops Core Strength and Improves Coordination Training with this medicine ball helps to improve the core strength in chest, arms and legs and also helps to improve muscular coordination. Enhances Balance and Endurance Use this medicine ball to improve your overall balance and endurance.