Brass Ferrule is made of soft brass or copper when used in MDPE pipes or plastic when used in PVC pipes. The ferrule is slipped onto a pipe and seated in a compression fixture adjacent to it.To avoid gas and water leaks in the plumbing system, a ferrule provides a sealed, compressed fitting.Brass Ferruleis a form of cap that is commonly used to provide a tight compression fitting in pipe and fixture junctions. When properly placed, these specific connectors help prevent gas and water leaks.