The Circulos glass downstem is designed to fit only into the Circulos center section. The downstem inserts into the top of the center section to complete the interconnection. The Fumo porcelain bowl sit on top of the downstem using a silicone grommet, which completes the connection between the bowl and the downstem. Once placed in the hookah the bottom portion of the downstem should extend about 0.5″ – 1.0″ inch into the water in order to make the hookah function properly. The downstem consists of an integral diffuser bottom, glass ground joint, which seals with the center section and a glass ground joint that allows for the porcelain bowl. The diffuser end is designed to reduce noise and increase cooling of the smoke as it passes through the water.