I bought this rear sight based upon feedback on a gun forum suggesting that it fit the BD2 and works better because of the reduced gap over OEM rear sight. I installed easily and validated that it is superior to the original.
It's maybe not the most high tech web site I've ever seen but all parts and laid out correctly and the pictures of the items are correct which is more than I can say for similar on-line sellers. All in all, I'm two thumbs up and I'd be three thumbs up if I had the 3rd arm I'm always talking about!