The nikon hn 30 lens hood is a 62mm screw in type hood for the nikkor af mc 200mm f4 d lens lens hoods are primarily designed to prevent unwanted stray light from entering the lens by extending and shading the end of the lens in addition since the end of the lens is extended you also get the added benefit of some extra protection from accidental impact dedicated lens hoods are designed to match the specific focal length of the lens it was designed for