Paul C. Fisher developed the pressurized refill for NASA in 1965. It's still in use 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, under water and at any angle-even upside down!
Key Features:
- Pressurized
- Space pen refill
- Parker Style
- Ball Point Refill
- SPR4F
- ** Writes Upside down
- ** Writes Under water
- ** Writes at -35°C - 121°C
- Colour: Blue
- NIB: Medium