The LifeCard .22LR / .22WMR by Trailblazer Firearms is a single-shot, folding handgun made to match the size and width dimensions of a normal charge card (3.375″ × 2.125″) using a thickness of roughly 0.5 inches. https://folding22pistol574784.bestblogskill.com/797288/overview-with-the-lifecard-credit-card-gun