A DI tailpiece, also known as a ductile iron tailpiece, is a component commonly used in plumbing and piping systems. It typically refers to a short section of ductile iron pipe with a specific purpose, often connecting two larger pipes or fittings. DI tailpieces are designed to provide a secure and leak-proof connection between pipes or fittings of different sizes or types. They are commonly used in situations where transitions are needed, such as connecting a ductile iron pipe to a valve, meter, or other equipment.