An ash catcher is bong part that catches ash, resin, and other debris before they enter the water chamber. It is typically placed on a downstem between the bong and the ash catcher part. This prevents dirty water buildup in your bong and leads to smoother hits with less cleaning required. Ash catchers come in different shapes and sizes with various percolators that offer additional filtration. When choosing one, it's important to consider joint gender, size, angle, and weight compatibility to ensure a seamless fit with your bong.