This hood screws directly onto the lens via a sleeve located inside the hood. The sleeve has a female E39mm thread, so you can screw in a E39mm filter as well, gone are the days of the series 5.5 filter held in by the rubber lens hood.
The hood itself is made from anodised aluminium.
The lens hood does come with a plastic clip on cap.
The installation process is the same as the summicron 35mm lens hood. Video below.
