This is a Fisher AG-7 Space Pen, the same model that accompanied Apollo 11 astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins during their historic flight to the Moon in July 1969. Still used today for manned spaceflight programs worldwide after its first mission with Apollo 7 in 1968, the pen uses black thixotropic ink sealed in a pressurized cartridge that enables it to write in temperatures from -30º F to 250º F, underwater, at any angle (even upside down) and in zero gravity. Its heft rests securely in the hand, the result of a chrome-plated brass barrel, pocket clip, and a click mechanism constructed from all brass and steel components of the highest quality that ensures its ultra-hard tungsten carbide ball retracts. Writes a medium line in black ink and lasts up to three times longer than ordinary ballpoints. Made in the U.S. 5 1/8" long. (7 oz.)