The exciting new Fisher Cartridge Pen is an actual .375H Mag Shell and is the perfect gift for the hunter or outdoor enthusiast. The pen cap is raw brass just as bullets are. There is no finish meaning that each pen is unique and one of a kind. With time and use a rustic patina will develop. It is recommended that you never fly with the .375 Cartridge Fisher Space Pen as TSA may not believe that it is an actual writing instrument! Like all Fisher Space Pens this pen writes at any angle (even in Zero Gravity) in extreme temperatures and underwater.