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 our chrome vanadium (CV) steel. Some knife lovers will settle for nothing less than chrome vanadium blades, since this special formula of alloyed steel is the "original" CASE blade steel. CASE chrome vanadium blades are known for their edge-holding ability and easy resharpening. However, they are less resistant to rusting, pitting and discoloration than stainless steel.