This red Gym Ball is 550mm (21.5\") in diameter and is an inflatable vinyl ball that is the ideal exercise aid for helping a user to improve their flexibility, coordination and balance.Made by Gymnic, this high quality Gym Ball is perfect for use in a wide range of therapy situations, sporting environments and gymnastics training. This bright, colourful red Gym Ball is made from hard wearing PVC, has excellent dynamic performance and is recommended for use with extreme loads such as aerobic exercises and for use as a sitting ball. The Gym Ball has a seamless construction and an impressive maximum load capacity of 300kgs (47 st), making it burst resistant during normal use. The Gym Ball is available in a wide range of different diameter sizes all of which can be found in this area of our site. Please note that the Gym Ball is supplied flat and deflated and will require inflation prior to use.