4" 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 (-50°C), extreme heat (+200°C), over wet paper, in a vacuum, and at any angle, even upside down.