ET%2D67B Lens Hood for EF%2DS 60mm f%2F2%2E8 Macro USM Digital SLR Lens%2E Lens hoods are primarily designed to prevent unwanted stray light from entering the lens by extending and shading the end of the lens%2E In addition%2C since the end of the lens is extended%2C you also get the added benefit of some extra protection from accidental impact%2E