A bong downstem is an essential component of a water pipe or bong that connects the bowl and bong. It is a tube, usually made of glass, with diffuser slits or holes at the bottom end to help filter and diffuse the smoke.

When using a bong, the glass downstem is inserted into the water chamber, which allows the smoke to be pulled down into the water. As you inhale through the mouthpiece, the smoke will pass through the downstem and be diffused into the water. This process helps to cool and filter the smoke, providing a smoother and more enjoyable smoking experience. It is important to choose a downstem that matches the size and joint type of your bong. And Phoenix Star is various sizes and joint angles available.