BODY TRENDS AB EXERCISER BALL 9" PROFESSIONAL GRADE exercise balance ball. This ball is intended for core strength, balance, back rehabilitation and for toning and sculpting the upper body. RECOMMENDED BY TRAINERS AND PHYSICAL THERAPISTS and for good reason. Exercise balls are perfect to increase balance, strength and flexibility. BETTER THAN MONEY BACK GUARANTEE. Made to be burst resistant. Should it burst within the first 90 days of use we will gladly refund you as well as provide a new ball.