What is this, hopod??? What is this, eyes hood???
If you want a lens hood, i suggest the Leitz IROOA that was originally foreseen for the Leitz M Summaron and Summicron 35 mm (with or without goggles), Leitz M Elmar 50 mm f/ 3,5 and f/ 2,8 and M Summicron 50, collapsible, rigid and D.R. Tha Leitz IROOA is a clip on lens hood, very useful.
As alternative, i suggest a step up ring B+W or Heliopan 39-40,5 (with 0,5 mm pitch!!!) and a normal rubber 40,5 lens hood.