Winglet
An upturned wingtip that reduces drag and saves fuel.
A winglet is the small, often near-vertical extension at the tip of an aircraft wing. By reducing the strength of the wingtip vortices that form as high-pressure air spills over the tip, winglets cut induced drag, which improves fuel efficiency and range — typically by a few percent. They come in several shapes, including blended winglets, sharklets, split scimitar designs, and raked wingtips.