Ridgid flex shaft machines utilize specialized chain knockers attached to a flexible cable that are spun at high speeds by a cordless drill attached to the center drive Shaft. Since the cable spins inside a durable nylon sheath that is housed within a fully contained drum, there is less jobsite mess. Chain knockers expand for full Pipe cleaning, which result in a wall to wall clean. This chain knocker features 5/16" Cable, 4" Pipe, 3 chain, and carbide tip.