Walter Knoll Foster 500 design is based on linear lines. Foster is a simply an icon of design that has classic yet contemporary approach. Walter Koll Foster has breathtakingly sweeping lines and contains generous space for an extra comfort sit. Choosing Refurbished: We love bringing these back to life with it being fully steam cleaned. Parts remain: The sofa will remain with its original material and framework. The frame may show signs of minor scuffs and wear. This will not affect the functionality of the sofa.