Containing a Fisher Space Pen Pressurized Ink Refill Cartridge, the M4G will write upside down – at any angle, under water, through grease, in extreme temperatures (-30 to +250 degrees F), on almost any surface, three times longer than the average pen, and of course in the gravity free vacuum of space, and all are lifetime guaranteed for quality against all manufacturing defects – American Technology. Style:Cap Activation Finish:Lacquered Brass Length:5.375\” Check outFisher Space Pen Refillsfor this pen.