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This cute little thing is a Mini Revolver by North American Arms, one of many kinds.
They make quite a wide variety of small revolvers in .22 caliber rimfire cartridges, including .22 Short, .22 Long Rifle, and .22 Winchester Rimfire Magnum, and in a variety of configurations. Most have you pull out the axis pin to remove the cylinder for loading and unloading, but they do make a few different ones, like a swing-out cylinder hand ejector, and a top-break (I think actually automatic) ejector. They're all single-action, though they lack any kind of transfer bar, they have a really oldschool feature where there's a slot cut between each chamber on the cylinders which the blade-style rimfire pin on the hammer can be rested, leaving the action securely locked and the hammer unable to hit any of the cartridges (a bit like on some old cap and ball revolvers).
They also have some neat unusual ones, like one with a grip which the gun folds into, kind of like a folding pocking knife, and one which comes fitted into a belt-buckle, I guess if you wanted to open-carry in a really unusual way (you can just pull it out of its mount and use it as a 'normal' gun).
This is their smallest one, in little .22 Short, with some coins for scale. Most wouldn't look at a gun like this as anything else but an adorable novelty, but it is still a firearm, and it's one which could be concealed even on the beach.