The Classic Double Stack is a more than full set up from the start. With two percolators and 3 couplers you are well on your way to have a collection of mix and match glass. The percs are 7 stem each and all of the glass is 5mm thick. The beaker bong joint is 18mm. With three couplers and our modern modular design you will be able to purchase additional percs to mix and match with in the future. It pulls smooth and comes apart easy to give it a good cleaning. This is especially nice for bongs with multiple tiers of percs as anyone who's owned one knows.