The basic structure of a bong consists of a bowl, downstem, percolator, and base. When the user lights the bowl containing their preferred product, smoke is produced which is then drawn down the stem and into the water-filled percolator chamber at the bottom of the water pipe. This acts as both a filter for any extra debris that may be present and also cools down the smoke before it is inhaled. The cooling effect helps to reduce harshness on the throat when inhaling allowing for easier, smoother puffs without skimping on flavor.