The Fisher Space Pen range was designed for use in Space when astronauts began to explore the reaches of outer space. Paul Fisher realised that there was no existing pen which could perform in its freezing cold, boiling hot vacuum. Countless experiments and a common sense approach to findings resulted in the invention of the sealed and pressurised Fisher Space Pen cartridges and in 1967 the Space Pen was selected for use by astronauts.
2008 saw the 60th Anniversary of the design classic the Fisher Space Bullet Pen, which today is the most popular selling item in the Fisher Space Pen range. The Bullet Pen is given its name due to its bullet shape appearance looks and feels like the ultimate write weapon. The sealed pressurised ink cartridge writes in almost any condition the Space pen refill writes at -30 degrees F (-34 degrees C) to +250 degrees F (121 degrees C), underwater, at any angle, even upside down.
So with that said you could say that the Fisher Space Pen refill is the most advanced writing instrument in the world.