The Tamron DA09 Lens Hood is created especially for the Tamron SP AF 17-50mm f/2.8 Di-II and SP AF 28-75mm f/2.8 Di Lenses. Lens Hoods are primarily designed to prevent unwanted stray light from entering the lens creating lens flare and improving contrast and image quality. A hood also extends the length of the lens, assisting with keeping debris, moisture and dust away from your precious glass and protecting your lens from accidental impact damage.