A DI collar, or ductile iron collar, is a component used in piping systems to join two sections of ductile iron pipes together. It typically consists of two halves that encircle the pipes and are joined together using bolts and nuts. These collars are designed to provide a secure and leak-proof connection between pipes, ensuring the integrity of the piping system. They are commonly used in water distribution networks, sewer systems, industrial piping, and other applications where reliable pipe connections are essential.