Info Needed on the MC W. ROKKOR-X 1:2.0 f=28mm

I just won the MC W. ROKKOR-X 1:2.0 f=28mm and I can't find much info on it anywhere. Only a short sentence saying that it was an excellent lens and has a floating element. Anyone have more info on this lens? I plan on keeping it and need to know if anyone has any experience with it, or know its faults and best use practices.

Thank you

Craig