Cartridge: Fisher Pressurized PR4, Black Ink, Medium Point Color: Brass Barrel / Black Ink Point Size: 1.1mm Ball Refill Length: 3.51’’ Packaging: Refill Cartridge Blister Card Fisher Space Pen’s Sealed Pressurized Ink Cartridge performs in temperatures from -30º F to +250º F, 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. Our regular PR Cartridge will typically write more than 12,000 feet depending on style and surface. ALL PR cartridges come with a plastic adapter which allows them to be used in Parker Style Pens! (Adapter dimensions – Length: 1’’ / Width: 0.23’’)