19-22mm/16-19mm extendable Double Layer Room Darkening pole. A simple, clean design, the double room darkening curtain pole effectively blocks out light. Its innovative wrap-around design helps prevent light leakage by allowing your curtain or drapery to rest directly against the wall. Wrap the curtains and voiles around the curved end of the pole and tuck it behind the bracket end stop screw to eliminate exterior light from seeping in. The double pole will help insulate your room blocking out drafts.