Lovit Scientific Fitness Ball - Ideal for Yoga and Core Exercise - 55cm BURST PROOF SAFETY Whether you use it as a core exercise ball, a yoga ball or a Pilates ball, you can count on this exercise ball to stand the test of time, as it has a burst resistance rating of 500 pounds SATISFACTION GUARANTEED This yoga ball chair and fitness ball for exercise is backed by a 30-day money-back satisfaction guarantee. You'll love it or we'll refund your money AN IDEAL SIZE FOR EVERYONE Choose the exercise ball 55cm size for 5'0" to 5'5" height, the exercise ball 65cm size for 5'6" to 5'11" height