Classic Fisher Space Pens have been going into space since before the first Moon landing. The cartridges of conventional ball point pens are open to permit ink to be fed to the point. The secret behind the Fisher Space Pen lies in the unique design characteristics of the ink and the high precision manufacturing tolerances of the ball point and socket. The ink is fed to the ball point by gas pressure permitting the pen to write in any position. The cartridge is pressurized with nitrogen so that it doesn't rely on gravity to make it work. It is dependable in freezing cold and desert heat. It can also write underwater and upside down. The Zero Gravity Space Pen with black rubberized cushioned barrel and grip and American Flag imprinted on barrel has a very discreet triangular 3-sided design that gives the user writing comfort and control. People with large hands enjoy a wider writing instrument. A very strong tensile strength on the clip ensures the Zero Gravity will not fall out of a thin dress shirt pocket or even a thick nylon back pack. The zero gravity space pen is a single-hand operation with the plunger mechanism at the top of the pen Each pen comes in a gift box.