This is another one of the rare and hard to find lenses for the Mamiya NC series. So far, I´ve only seen it on eBay three or four times. Since November 2002 I am now also a proud owner of this very nice lens.
The lens is surprisingly light-weight for its size. It has a built-in lens hood and also a tripod mount. The large minimum focusing distance of 5 meters is quite a drawback in my opinion.
I haven´t had a chance to test the optical performance of this lens, but I would assume that there is quite a bit of chromatic aberration due to the lack of special dispersion glass.