The product is a Canon RF to EF adapter, allowing Canon EF lenses to be used on Canon RF mount cameras.
Never been used. Canon RF body to EF lens. If you have an RF body you can use this adapter to use more affordable EF lens.
Accidently, bought the wrong thing. Costs $170 new. Her's a link if you want to check out he product more.
https://urth.co/products/canon-ef-ef-s-lens-mount-to-canon-rf-electronic?_pos=2&_psq=ef-rf%5C&_ss=e&_v=1.0