This is a really good condition Mamiya 645 55mm f2.8 C lens, including both caps.
This lens has is in great mechanical condition. No problems at all, aperture really fast without any sticking. This lens is quite well used but has perfect glass. There are obvious signs of use on the mount and barrel, plus a slight dent in the filter ring that may stop you fitting filters. The price takes this into account.
Now seriously hard to find; this is still a really nice lens. If you want a better 55mm lens, I have a near mint 55mm N example in my other listings (as at 1 October 2025 anyway).