’59 Mattel Agent Zero gold derringer, part of the Agent Zero belt buckle/derringer combo. The derringer was modeled after an 1867 Remington and used a single shootin’ shell. Once loaded and ready, all one had to do was push one’s stomach out – the derringer would swing forward and fire the projectile.
Mattel also sold the derringer without the buckle accompanied by a wrist holster: The Potshot.
The Potshot came out in 1965 and coincided with The TV show The Wild Wild West. Robert Conrad played James West and sported a quick-draw derringer sleeve gun.