The Adidas Stability Gym Ball features a weighted base which offers additional grip to prevent it from rolling during use for more effective workouts. It is one of the most versatile pieces of fitness equipment that is suitable for users of all fitness levels. This premium quality exercise ball is manufactured from anti-burst material and offers an ideal balance between support and instability. It is an excellent tool to increase core strength, develop balance and improve overall fitness. The 65cm diameter gym ball includes a hand pump and workout chart and is most suitable for users between 5' 7" and 6' 1" tall.