M4 Cap-O-Matic Series. 5 1/8" closed. This unique design engages the point with entire pen top. The standard top button has been removed to create a sleek, easy-to-use writing instrument. Aluminum construction. Red barrel with chrome cap. clip and tip. Loaded with medium point black ink cartridge. Uses Fisher pressurized refill FP1211 (blue ink) or FP1241 (blank ink). 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 down.