the instructions were a bit unconvincing as that's what is being posted here. and while I know they are fireproof, and that is an important factor, they are stiff and difficult to manoeuvre; In fact, the glass I chose was almost folded in half when I put it in. I probably won't be buying any more of these and while they would be good for a shop or bar with a lot of smokers daily, it's not worth it for me as I can just empty the jar in the jar every month or so. as easy as messing around with this thing.