Disposable, Waterproof ink, Fade-resistant, Durable lettering art tools, Produce crisp edges and sharp hairlines without the need of ink wells, ink cartridges or removable pen nibs, They have a firm, flat nylon nib that withstands heavy pressure and repeated use, and still provides a reliable, smooth ink flow from edge to edge, Meets ASTM and ACMI non-toxicity standards and is AP seal certified