This .50 caliber bullet cartridge pen kit will make a great gift for any outdoorsman or a military enthusiast. First developed for the Browning, a .50 caliber machine gun in the late 1910's, the cartridge used in this kit is commonly used in the military. Utilizing an authentic .50 caliber once-fired brass cartridge, a single 7mm tube, and a Cross style ballpoint mechanism, we've made it easy for you to turn this one-of-a-kind pen. You can vary the length of the turned section from 1-1/8" to 2" for a custom appearance. Overall size of the bullet pen is 5-1/2" to 6-3/8".