The Canon CB3-7903-000 multicontroller button is a replacement camera control component for restoring the multicontroller’s physical control point. It is listed as a Canon spare part under the exact manufacturer item code CB3-7903-000.
The part is identified as the multicontroller button, also described as the MC joystick. A specialist parts listing associates this component with the Canon EOS 5D Mark III and EOS 5DsR cameras, making it relevant for repair work on those models.
This is a specific button component, rather than a complete multicontroller assembly. The confirmed model references are Canon EOS 5D Mark III and EOS 5DsR.