A flare gun. What can I say? It's used to put a flare into the air. I could go into technical details, but there isn't much to say. Striker-fired, single-shot, manually-cocked, break-action, 12-gauge flare gun. The grip has two extra flares inside in addition to one in the chamber. The only metal parts are the striker, spring, and breechface. Everything else, including the barrel, is injection-molded plastic.

Which means you don't want to fire shotgun shells out of this. Yes, you can load standard 12-gauge shotgun shells, but you'll blow off your hand if you do. However, there are caliber conversion sleeves that let you fire .22 rimfire out of this. Not that it will be any good for anything, but they are there. Also, even though this isn't really a weapon, it will hurt if you shoot someone with it. Because the flare projectile is really a large chunk of burning potassium nitrate and magnesium.