Paul C. Fisher developed the pressurized refill for NASA in 1965. It is still used today on manned space flights because it performs when other pens fail. The combination of tungsten carbide ball point and thixotropic ink in a hermetically sealed cartridge pressurized at nearly 35 pounds per square inch allows it to write in freezing cold, boiling heat, underwater and at any angle - even upside down!
These refills come with an adaptor that transforms them to fit perfectly into any ballpoint pen that accepts a Parker-style refill (international ball point refill).
Length: 3.5" (8.89 cm)