The Condux 3-1/2" Rubber Duct Swab is ideal for cleaning and assisting in the spreading of lubricant throughout the duct as well as testing its integrity during cable installation. It is made of rubber discs on a braided steel cable with pulling eyes at each end for strength and versatility. The rubber discs provide a secure grip that helps you get to hard-to-reach places, while its robust construction ensures reliable performance in any environment.