Manufactured in the 1960s, the Mark I Gyrojet uses a 13 mm solid fuel rocket in place of a standard bullet and cartridge. As the rocket does not require a solid chamber to contain ignition nor extractor equipment to eject a casing, the entire pistol is greatly simplified and constructed from mostly lightweight materials. Features adjustable blade front and fixed notch rear sights, front-mounted hammer, "MARK I/MODEL B" marked on the left side, and a pair of smooth walnut grips. Includes a MBAssociates "Rocketeer" box.