Design space: Diffrient World chair By Clare Dowdy Design: Niels Diffrient Territory: US The US manufacturer of ergonomic office equipment Humanscale wanted to produce a chair with as few parts as possible, making it lighter to transport and quicker to assemble. Standard task chairs - those designed for people to work at a desk or table - have more than 100 parts and weigh roughly 25kg. Much of the weight of a standard chair is in its manually operated height and backrest adjustment mechanisms, usually involving a spring. The late US designer Niels Diffrient had created a spring mechanism for earlier Humanscale task chairs, which used the motion of the sitter's weight on the seat to adjust the backrest. For the Diffrient World chair, he designed a counterbalance mechanism that achieves the same effect with fewer parts. Instead of a spring this chair uses gravity and friction to set the recline tension of the backrest. The frame of the backrest curves under the seat following the sitter's thigh line. Within two channels under the seat are two small rubber rollers. As the user sits down, the base of the seat slides away from the backrest and over the the rollers. This allows the individual's body weight to set the tension of the chair. The chair has 31 parts and weighs 13kg. It has been on sale in the US since January 2012 and will be sold globally later this year.