Alvin - Original Penstix Marker - 0.5mm - The Alvin Original Penstix Marker is a unique high performance marker that produces crisp, sharp lines for freehand drawing or for use with a straightedge. 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. Favored by cartoonists worldwide. The durable plastic fiber nib will not clog. Available individually in three line widths (0.3mm, 0.5mm, 0.7mm) or as a set of three. Alvin Penstix feature convenient pocket clip and ribbed cap that fits snugly on the barrel.