PEL301135 Pelikan 4001 Fountain Pen Ink, Royal Blue, Liter. Pelikan 4001 Fountain Pen Ink - Pelikan's first writing inks were called 4001. The reason for this name was a designation found in the Receptu Buch which was used to record formulas for different product lines. Writing ink formulas were in Book Four and the first formula was recorded as 001. Hence the designation "4001". 33.82 oz - Liter (1000 ml) bottle.