The AOK MediBall is, in our opinion, the best ball on the market and the ONLY one we will use in our classes. Made right here in Australia from the highest grade materials, it offers you full support for your back and pelvic floor while engaging your core for long term stability and strength. Use it together with the Preggi Bellies DVD, as well as the perfect alternative to a desk chair while working.The size we ship out is a medium (65cm) and is appropriate if you are taller than 5 ft and shorter than 6 ft. If you are 5ft or less tall or you are 6ft or taller please call us to special order a ball for you height.