it's not called a lung bong....just a lung...and all it is, is cutting the bottom of a two liter off and sticking a bag that is the same size as the two liter on the bottom so that on the top there's a plastic bottle wtihout a bottom and then a bag taped air tight to it.....then you push the bag up inside the plastic bottle put a bowl on the mouth peice and then as your lighting the bud slowly pull out the bag...it sucks in smoke and makes for some pretty fuking huge hits.....if it's hard to understand sorry i can't expjlain any better...i could maybe take a picture if that would help