Us duct’s laser-welded clamp together ducting (ctd) uses a gasketed, over-center clamp that seals the rolled lip on the end of all clamp-fitting ductworkcomponents.it installs in seconds without screws or welding cutting your installation time down by 70% or more. available in 3″ to 24″ diameter and ranging from 22 gauge to 10 gauge metal to handle the toughest applications.