Product Number: SC4

Black Ink Fisher Refill for Cross Pens - Medium Point.

Unlike ordinary ball pens which rely on gravity to feed ink, the Space Pen’s replaceable cartridge is pressurized. At nearly 50 pounds per square inch, ink is continuously fed to the tungsten carbide ball, allowing the user to write at any angle, even upside down. This advancement required the development of a special ink.
 
The new visco-elastic ink, with a consistency similar to that of very thick rubber cement, flows as a result of the shearing action of the rolling ball in its socket.. This shearing action liquifies the solid gel thixotropic ink, allowing the pen to write smoothly and dependably on most surfaces and even under water. Evaporation, wasted ink and back leakage are eliminated. Shelf-life is increased to an estimated 100 years.

Operating conditions:

• Writes underwater and on wet surfaces
• Not affected by cold damp conditions
• Writes on most smooth surfaces
• Writes in extreme heat and cold
• Pens operating range is -50° F (-45° C) to 250° F (121° C)
• Writes at any angle.