First one I have seen, but just finding a real SD is almost near impossible. I zoomed in and looked at the rear sight closely. Looks like it was milled during the manufacturing process and was NOT an afterthought. If you look closely, the blueing where it was milled was done during manufacturing. In other words it was not manufactured, milled , and then had the rear sight installed. Very rare indeed! It’s now at $20k. I wonder what it will sell for.