5.6mm Highlighter Lead
A set of three leads in fluorescent yellow, orange and green so that your clutch pencil can be turned into a highlighter. This is a wonderful system that allows pencils to be refilled rather than highlighter markers thrown away. This works well with Kaweco's Sketch Up Pencil or other clutch pencils which take a 5.6mm lead.
Kaweco was established in 1883 outside Heidelberg Germany, although it was not yet called Kaweco and the design that is the most recognizable, Kaweco Sport, was not designed until 1911. A fountain pen that was not a heavy, expensive desk piece but rather lightweight and convenient was an innovation. Ballpoint pens, what we would think of as an analogy to this experience, were invented in 1888 but a reasonably functional design was not produced until 1938 and popularization came mostly after World War II, by then the Kaweco Sport was a classic as well as many other designs produced by Kaweco.