A percolator is a device for a water pipe or a bong that is meant to filter and cool the smoke for a smoother hit that should also reduce coughing. There are many different types, shapes, and sizes of percolators; they are usually in a dome shape, but many different designs are available to fit inside the tube of different bongs. A percolator provides an additional water chamber for your bong and efficiently filters smoke by providing another opportunity where the smoke can make contact with water and the bubbles produced by the percolator. This added water surface area provides an added filter for smoke to reduce more contaminants and further cool down the smoke for a smoother hit.