This amazing Space® Pen from Fisher Space Pen Company allows you to write in any environment. It can write at any angle in all weather conditions, even upside-down underwater! Used on all manned space flights, they're the only type of pen that will work in the freezing cold (to minus 50 degrees F), boiling heat (to 300 degrees F), and even gravity-free conditions. It writes cleanly, even over grease and fingerprints. The ink is permanent, containing pigments as well as dyes. Unlike ordinary ball pens that rely on gravity to feed ink, this Space® Pen utilizes a replaceable sealed pressurized metal cartridge. At nearly 35 lbs per square inch pressurization, the ink is continuously fed to the tungsten carbide ball, allowing the user to write at any angle. The 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 liquefies the solid gel thixotropic ink, allowing the pen to write smoothly and dependably on most surfaces. Evaporation, wasted ink, and leakage are eliminated and shelf life is increased to an estimated 100 years. Space® Pen Color: Black. Ink color: Black. Made in USA. Available in 3 styles: standard (plastic barrel with chrome plated cap), rubber-coated for contemporary "soft feel", and military (all metal U.S. military version). A pressurized ink cartridge is included with each Space® Pen.