Tempo was an Austrian writing-instrument maker (Vienna firm Gerspacher) that in the 1920s to 1940s produced numerous standard pens, also push fillers, in various colours. A comprehensive documentation or catalogue of Tempo does not exist; only the Vienna restorer Leo Grahofer (grasshopper.at) has documented some on the brand and is the central contact point for questions and restorations (cleaning, new piston). A short mention is also in the Penkala book by Miroslav Tischler in the chapter on Austrian makers. Original nibs usually carry the imprint 'Tempo'.