The Koh-I-Noor® Radiograph® technical pen is an ideal choice for artists, designers, architects, engineers, and hobbyists alike. Featuring quality stainless steel nibs, this refillable technical pen provides precise and consistent ink lines. It has a line width of 0.25mm, thus letting you draw fine and detailed lines. In addition, a double-seal airtight cap prevents the nib from drying out. This Koh-I-Noor technical pen works on a range of surfaces like vellum, paper, and tracing paper.