Discs are flat, grooved plastic rings with a hole in the center. Rings are stacked together to form a cylindrical filter element. The grooves in the rings criss-cross, forming a network that traps both organic and inorganic contaminants, and allows filtered water to pass through. For easy cleaning remove the cover exposing the discs. They automatically separate allowing access to the accumulation of dirt particles. Wash off the discs with a stream of water, reassemble and the cleaning process is complete. A filter should be used with all Netafim watering systems.