unused and in perfect condition One of the most useful fountain pens ever manufactured is the Parker 21, the World's Most Sold Fountain Pen. It's hard to break, never leaks, and always functions. The Parker 21 pen was the first to have its nib hidden beneath a hood. This design decision was made to prevent ink from drying out during the journey from the ink reservoir to the paper. The body of the pen was fashioned to resemble a jet fighter from the side, and the glue used (Lucite) was the same type of material used in some wartime aircraft nose cones. Parker 21 Black, Brushed Steel Cap, Stainless Steel Fine Nib, and Scratch-Resistant Lacquered Finish with Shiny Chrome Trim Included Parker Squeeze Converter for Ink Incorporate Parker Quink Ink.