Fisher Space Pen

Fisher Space Pen, Bullet Space Pen with Clip, Chrome, Gift Boxed (400CL)

Paul Fisher, wishing to improve upon his universal pen refill, invented the anti-gravity cartridge in 1965. The engineering is quite interesting.  "After much experimentation he perfected a refill using thixotropic ink-semisolid until the shearing action of the rolling ball liquefied it-that would flow only when needed. The cartridge was pressurized with nitrogen so that it didn't rely on gravity to make it work. It was dependable in freezing cold and desert heat. It could also write underwater and upside down."  The original AG7 model is actually used in space missions by both the US and Russia. The Bullet is a popular compact model.  The Fisher Space Pen Co. and manufacturing are in Boulder City, Nevada.