Voigtlander lh 1 lens hood
This lh 1 lens hood from voigtlander is a dedicated lens hood for the voigtlander 21mm 25mm and 28mm lenses lens hoods are 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