Penexchange

During World War I, Mabie Todd's British manufacturing activity was devoted to munitions production, retro bowl while the related company in the United States supplied stockpiles of Swan and Blackbird pens to the British market.

One of the quickest and simplest methods to tell the two models apart is perhaps by looking at the feed. A hard rubber (ebonite) feed comprised of four vertically arranged fins was installed on the 400. The plastic M400 feed is made up of numerous longitudinal fins.