Percolator

A water-pipe component (often a chamber or honeycomb disc inside a bong) that breaks rising smoke into smaller bubbles to increase contact with the water. The result is cooler, smoother smoke. Common percolator designs include tree, honeycomb, showerhead, inline, and fritted disc. High-end bongs may stack multiple percolators for additional filtration. Adds drag (resistance) — too many percolators can make a piece difficult to clear.