Powerstretch exercise balls, also called gymnastic, stability, fitness, physio balls or swiss balls are used for safe & effective exercise, flexibility, fun, improving strength, losing inchs, correcting bad posture, balance and physical therapy exercises. powerstretch exercise balls are made of highest quality vinyl like duralon with burst-resistence technology which means the ball will not explode if accidentally punctured. the product is bundled with inflator & measuring tape.