With this Metabones EF to RF adapter you can now mount full-frame lenses to the new Canon RF mount. ( Cameras include C70, RED Komodo, Canon R) People who hire this adapter are now able to mitigate most of the 4k video crop factor of EOS R (1.75x) and EOS RP (1.63x) and reduce it to 1.24x and 1.15x respectively. The field of view is now much closer to still photo mode. A super 35mm Sensor becomes full frame so those gorgeous wide lenses you have are now unleashing the full potential.
This adapter will also allow you to increase maximum aperture by 1 stop. (with a maximum output aperture of f/0.9)