Canon USA has stock of the Canon EF to EOS R control ring adapter.
Mount Adapter Allows EF/EF-S Lens Compatibility with the EOS R Camera.
Built-in Control Ring Provides Quick Access to Camera Functions.
Exterior Design Matched to EF Lenses.
Dust- and Water-resistant.
Metal Mount on Both Lens and Camera Sides Provide Rugged Flexibility.
Canon EF – EOS R Control Ring Adapter at Canon USA (Update: now showing out of stock)