The writing parts of the Fisher Space Pen are designed for more than just outer space. Thanks to its patented sealed and pressurised ink refill, you can write in almost any conditions and on almost any surface. Underwater or on grease. Extreme temperatures (-30 to +250 F / -35 to +121 C). Upside down or floating in a gravity-free zone. Sealed and pressurized ink refills last three times longer than the average biros with an estimated 100-year life.