The Cap for this exciting new Space Pen model is an actual .338 H Mag Shell. What a special gift for the hunter or outdoors enthusiast! Inside is a laquered Brass Bullet Space Pen. When closed, Bullet Space Pens are the perfect size to carry in your wallet, pocket, purse, car glove box, organizer or toolbox. When open it"s a full sized, evenly balanced writing instrument. The original Bullet Space Pen was conceived in July of 1948, Paul Fisher was soon machining a new pen design shaped from solid aluminum. It became our first Fisher ball point pen, the 400 Bullet Pen, and arguably the most popular pen of the twentieth century. This pen is now all brass with a raw Brass finish.