These chairs are very heavy, the legs are made of thick, heavy cast aluminum which supports a tough injection molded two-piece hard plastic shell covered in two-tone leather. This design is published in Carlo Belloli´s monograph on Hesterberg´s work entitled ´´Knut Hesterberg, Skulptur, and design´´. The book confirms that these chairs were only produced for a maximum of two years between 1970-71 by the ´Selectform´ atelier in Stuttgart, Germany and were retailed through the ´Design-Center´ Stuttgart, Germany. The book confirms production ceased in 1971. This design featured in the prestigious Sothebys´ London sale ´20th Century Decorative Arts selected by Gordon Watson´ in September 2007 where a pair of Hesteberg lounge chairs were estimated at £6-8000 pounds circa $12-16000, so this pair is priced competitively.