lol we used to have one of those it was great fun to jump on someone and hold that thing on till they went limp. But it was scary as hell when it happend to you. we never smoked out it by choice.
Those things aren't all they are cracked up to be. I had one of those once and it's fucking hard as hell to get a good hit. And your oxygen supply doesn't last long at all so you still have to pull the mask off every 15 seconds or so. Totally not worth it.
i made one with a wwII gas mask from a yard sale, a pvc pipe and cap and bong slide. shit hit retarded, it took a whole breath to bring the smoke up the chamber and another one to clear it.