The comfy work seat that beats back-ache Standard office chairs, even ergonomic ones, are the biggest cause of back pain amongst office workers. The Pilates-style ball forces you to sit up straight, so your spine curves correctly but the gentle motion also gives your core muscles a mild work-out. Recognised by the Canadian Physiotherapy Association, Evolution Chair has thousands of fans all over the world who, like us here in the office, find they are rarely troubled with back pain any more once they use it instead of an ordinary office chair. Made from tough, anti-burst material, Evolution Chair is adjustable for height & can be used with wheels or static legs. Suitable for anyone from 5ft to 6ft 5in. With regular use you are guaranteed to notice improvements within 6 months or your money back.