Does anyone know what that small metal briefcase that you put a hot stone in is called? It's supposed to disperse the residual heat passively and safely from the rock inside that you heat up in the campfire or something like that. I've seen it on some japanese camper's video but I can't find it anymore. And if anyone would have a peek at my search history of me trying ti find the name of the thing they'd think I'm retarded. thanks bros