All pen knives have in common two blades on opposing ends. Varying in length from 2-5/8 in to 3-3/8 in closed, you can pick the one that best suits you. The clip blade which sits on the pocket end while the pen blade sits on the cap end. The clip blade is commonly used as a multi-purpose blade and preferred for detail work. The pen blade is great for small detailed uses, especially for everyday use such as opening envelops and boxes. This knife is constructed with CASE Tru-Sharp™ stainless steel which is a special high-carbon steel that helps the blades hold an edge longer than conventional steel. It also offers extraordinary blade strength and corrosion resistance.