77mm Soft Rubber Lens Hood For Canon EF 400mm f/5.6L USM Super Telephoto Lens + Cap Keeper + MicroFiber Cleaning Cloth + LCD Screen Protectors

Universal Professional Tulip Lens Hood is primarily designed to prevent unwanted stray light (flare) 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. Screw-mount lens hoods, such as this, are designed to screw right into your lens or filter.