The Tamron DA18 Lens Hood for 18-250mm & 18-270mm PZD Lenses, is designed to prevent unwanted stray light from entering the lens even at the telephoto end of high-magnification zooms. The lens hood is extended in order to shade the end of the lens and to benefit of some extra protection from accidental impact on the lens. Additionally, the shape of this hood prevents vignetting for wide shots.