A product of the 1960s, the Mark I Gyrojet uses a 13mm solid fuel rocket in place of a standard cartridge. As the rocket does not need a solid chamber or extractor equipment, the entire pistol can be greatly simplified and made from lightweight materials. Fixed blade front and fixed notch rear sights, front-mounted hammer, "MARK I" marked on the left side, and a pair of smooth grips. With a hardwood MBA display case, ten dummy rounds, and 17 live rounds of Gyrojet ammunition as well as a MBA certificate of authenticity.

Excellent overall, retaining 99% plus original black finish with limited handling marks and some wear on the small parts. Safety needs adjustment, otherwise mechanically excellent. Case is very fine with some light storage and handling marks and light high edge wear on the lining.