Fisher Space Pen Trekker Tactical Pen4" overall. Black rubberized body with posi lock cap. Pressurized thixotropic, visco elastic ink cartridge ensures pen will be ready to write even upside down, underwater and in extreme temperatures. Built in keyring, break away lanyard and carabiner included. Hang packaged. Writes reliably under extreme conditions: over fingerprints, over grease, extreme cold ( 50C), extreme heat (+200C), over wet paper, in a vacuum, and at any angle, even upside