Replaceable pen nib for the Sport Fountain Pen. Newer Sports use a nib that unscrews, making it easy to replace. If you have an older model it can still be replaced, by pulling the nib out of the pen body. *The demo models were used briefly for demonstration purposes. Blank ink was used and cleaned after use. A tiny amount of residual ink may be left so if you are using a lighter color ink it may show a little darker temporarily until it is spent.