Fisher Space Pen - #FM4C/GR Chrome/Green Cap-O-Matic with Powder Green Cap Style: Cap Activation Finish: Chrome with Powder Green Cap and Chrome Clip Length: 5.375" Cartridge: Fisher PR4 Black ink Medium point Packaging: Gift Pack Box Originally the Fisher Space Pen was developed for the NASA Apollo mission and it""s characterized by its extraordinary writing features. The gas pressur catridge permits writing overhead, under water, in great heat (up to 392° F), in freezing cold (down to -58°F) an in zero cravity. The catridge lasts three times longer than a common ballpoint pen catridge.