The black LH-48B Lens Hood for M.Zuiko Digital 17mm f/1.8 Lens from Olympus is a metal lens hood designed specifically for the above mentioned 17mm f/1.8 lens. The primary purpose of a lens hood is to deflect unwanted light from entering the lens and producing flare. It can also provide a degree of protection for the lens from accidental impact and the elements. A dedicated lens hood is designed specifically for the focal length of its lens and provides enough extension to deflect light without intruding on the image frame.