This is a very nice Canon FD Prime Lens 20mm f2.8
I've had it checked over by an expert and the report was as follows:

The iris mechanism works correctly, mounting to a camera body is fine,

infinity focus is spot on and the focus is smooth.

I have adapted it to be used with a Sony FS7 and a Sony A7sii for video recording

along with an adapter from MTF and it works perfectly.