The GH-1 Lens Hood & Adapter from Ricoh is a two-piece set of lens accessories for the GR Digital II and GR Digital cameras. The adapter twists & clicks onto the body, bayonet-style.
The adapter allows you to screw in a filter that has a 37mm diameter. You can also attach the lens hood to the front of the adapter. The lens hood features a ridged interior surface that's designed to deflect light and prevent flare. It will also serve to protect the camera's lens from accidental impact.
The adapter is required for using Ricoh's GW-1 0.75x wide conversion lens or GT-1 1.43x teleconverter lens with the GR Digital and GR Digital II.