This is an excellent condition Mamiya 645 55mm f2.8 C lens, including both caps.
This lens in is perfect mechanical condition. No problems at all, aperture really fast without any sticking. This lens has the normal minor paint loss on the lens mount. The glass is almost perfect with just a few pinprick size marks on front coating that will not have even the slightest effect on your images; there are no other optical issues.
Now seriously hard to find; this is a really nice lens.