I bought this down stem to replace the silicone down stem that came with my silicone bong. The glass one works so much better than the original. It's made of nice thick glass and it fits perfectly snug in my bong. My bong chugs like a freight train now. Also the bowl comes out of the glass easily, instead of sticking, like in the a silicone down stem.
Purchased these so I can make my own bong.