Pen & Ink Fountain Pen Sketch Set - These beautiful pens come with the pen itself, an ink converter (for using ink out of a bottle), three ink cartridges, and a suede wrap. The pen is designed with an iridium tip. The most corrosion-resistant metal known, iridium was first added to reinforce early pen nibs, which were made of gold- and thus too soft. It is the iridium point in contact with paper that makes the ink flow smoothly, and respond to variations in pressure. As it wears over time, the iridium tip will form to your particular style of drawing or writing, making this pen distinctly yours. Only use non-shellac based inks in this pen. Most water based inks do not contain shellac; inks that are sold as permanent ink usually contain shellac to make them waterproof. This type of permanent ink can clog the tip of your new fountain pen.