Looking for fountain pens online? Diamond Classic Black Fountain Pen is a Piston Filler type fountain pen. The innovative piston filling mechanism holds plenty of ink and you don’t run out of ink unexpectedly. This TWSBI fountain pen is sleek and features a classic design in Black. With a simple untwist and twist of the end cap, ink is drawn up and ready to write. The steel nib is reliably good and is comfortable for writing. The cap features threaded mechanism. Buy fountain pens online at William Penn!