This Tamron Lens Hood is compatible with their SP AF 180mm F/3.5 Di LD lens. Hoods are primarily designed to prevent unwanted stray light from entering the front element 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 hoods are engineered to match the specific focal length of the lenses for which they are designed.