Before revision: Compression fittings for attaching tubing (piping) commonly have ferrules (American English) or olives (British English) in them, and are sometimes referred to as flareless fittings.
After revision: compression rings, called,Compression fittings for attaching tubing (piping) commonly have ferrules (American English) or olives (British English) in them, and are sometimes referred to as flareless fittings.