The Penstix markers are a high performance illustration pen that produces crisp, sharp lines for freehand drawing or for use with a straightedge. The dense black ink will not bleed through most papers and is perfect for technical drawing, sketching, fine art, lettering, and illustration. These pens are a favorite of cartoonists worldwide. The markers durable plastic fiber nib will not clog. They have a pocket clip and ribbed cap that fits snugly on the barrel.