This is the rare full frame 37mm f/4.5 fisheye for the RB. (It will also work on the RZ, though you need to set the shutter speeds on the lens and metering will not work).
The lens is in good condition and works perfectly. The glass is clean and scratch-free and the shutter is strong and accurate. One of the four hood petal is slightly bent. This does not impinge on the image. The caps are included.