The Leitz Active Sitting Ball with stopper function encourages back and core muscle movement to improve posture and relieve back pain. Ideal for use as an additional sitting solution to keep you active while you work. IGR and TV certified. The 55cm diameter makes this sitting ball chair ideal for those between 135 and 155cm in height. The safety stopper function prevents the ball from rolling away when standing up and secure for storage. With it's minimalist design, this stylish sitting ball chair has a positive impact on wellbeing by effortlessly creating the perfect active working set-up. Alternate every 30 minutes between the ball and a chair and ensure correct inflation according to the manual. Combine with other Leitz Ergo products for an inviting and flexible workspace to help you stay active and productive throughout the day.