This vintage fountain pen is Parker's second version of the duofold model. This type of pen is referred to as the geometric or toothbrush duofold by collectors. They did not sell well originally and were only made for a short time between 1939 and 1940. Due to the limited time these pens were made and their attractive, unique design they are quite popular today. The cap of this pen is aged a different color than the body. Some discoloration is a somewhat frequent issue with these pens. This one has a name engraved in the side. I have not tested the usability but the pen is still quite nice looking.
Parker geometric duofold fountain pen