Downstem is an accessory for Cannabis smoking gear such as a bowl or bong. It is a lengthy piece of glass that connects the bowl of a bong or water pipe to the pipe’s body. As you inhale, the downstem creates a suction pressure that drags the smoke down through the mouthpiece. Downstems can either be removed or attached to the glass. A diffused downstem has a diffuser that aerates the smoke and makes it easier to inhale.
Downstem has various sizes to choose from: 10 mm, 14 mm, and 18 mm.