The extension tubes are plastic rods that can be inserted separately or together to add length to the hose. Brushes can be attached to the end of the extension tube and locked into place with the locking latches. (For NEWER KleenJet® models with the new yellow locking tab where the accessories automatically lock into place. If you have the older style "slide to lock" mechanism where you manually have to lock the attachments together, this will not work!)