In addition, since the end of the lens is extended, you also get the added benefit of some extra protection from accidental impact. Dedicated lens hoods are designed to match the specific focal length of the lens which they are designed for.
Type - Lens Hood
For use with - Canon EF 70-300mm f/4.5-5.6 DO-IS & f/4-5.6 IS USM Lenses
Colour - Black
Weight (g) - 0