Fisher Space Pen - #SPR6 3 Pressurized Cartridges Purple Ink Medium Point Purple Ink Medium Point Space Pen Pressurized Cartridge. This is Fisher""s standard 3 1/2 inch Pressurized Cartridge that fits most of Fisher pens. The Write Out for this Cartridge is approximately 15,000 feet depending on writing style - 3 times longer than a typical ball point Cartridge. The Fisher Space Pen pressurized cartridge performs in temperatures from -30ºF to +250ºF, underwater, in zero gravity, at any angle even upside down! The ultimate in dependability! The choice of ski patrols, search and rescue teams, law enforcement agencies, armed forces, and everyone who demands reliability in a writing instrument. All (S)PR cartridges come with a plastic adapter which allows them to be used in Parker Style Pens! POINT SIZES: Fine contains a .9mm Ball, Medium contains a 1.1mm Ball, Bold contains a 1.3mm Ball.