Cable Rotary Brush System with push button locks. Very flexible allowing it to make turns inside the duct easily. Cable system consists of hollow metal fiber/plastic sheath with braided steel cable inside it. 7 brushes of various sizes from 4″ to 18″. Nylon and silica carbide brush bristles. Easy push-button locking brush heads make changing brushes quick and easy. Available in 15′ and 25′ lengths.