Canon EW-83J Lens Hood for EF-S 17-55 F2.8 IS
Bayonet, petal form, two-claw removable hood; attachable in reverse.The Canon EW-83J Lens Hood, like all other Lens hoods, is 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.