Alvin Penstix Drawing-Sketching Marker 3-piece SetAlvin Penstix technical markers are high-performance markers that produce crisp, sharp lines for freehand drawing or for use with a straightedge. Excellent for technical drawing, sketching, fine art, lettering, cartooning, illustration, or for most any other form of graphic arts. The dense “India Ink -quality” black ink will not bleed through most papers and is perfect for technical drawing, sketching, fine art, lettering and illustration – any project that demands high quality results. Favored by cartoonists worldwide. Durable plastic fiber nib will not clog. Available individually in three line widths (0.3mm, 0.5mm, 0.7mm) or as a set of 3. Penstix now include a convenient pocket clip and a ribbed cap that fits snugly on the barrel.