Grav Labs designed these Upright bubblers to be as compact as possible but still deliver a satisfying experience. They have a wide 44mm chamber for maximum capacity and the fixed downstem has a multi-slit diffuser to break up the smoke as quickly as possible. At the top of that is a 14.5mm female ground glass joint. The extra wide base makes them super stable so it's a perfect addition to any coffee table. Grav Labs also include a flower bowl with 14.5mm male fitting to get you going straight out of the box.