Fisher Space Pen - #FM4GR/CT Powder Green Cap-O-Matic Style: Cap Activation Finish: Powder Green with Chrome Clip and Nose Tip 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.