AppleRound Set of 2 Pilates Mini Exercise Balls, 9-inch (23cm) Diameter for Pilates Yoga Fitness Exercises Includes TWO balls. Each ball is 9 inches (23cm) in diameter and 90 grams in weight, featuring soft surface for increased comfort. An ideal tool for Pilates Yoga Fitness Exercises. Ball are inflatable and delivered deflated. Straws and plugs are included for easy inflation and deflation. Made from EU approved phthalates free PVC & contain no heavy metal elements. Conforms to the safety requirements of EU EN71, US CPSIA & ASTM F963. Safe to use. How to Inflate: Remove the inserted white plug (air stopper) from the ball first, insert the straw into the hole, and blow the air from mouth into the straw to inflate, replace the white plug back quickly after the ball reaches good size. How to deflate: Remove the inserted white plug (air stopper) from the ball first, insert the straw into the hole, press the ball and air would escape fast through the straw.