BT-21262-1 is what I would go with. For $120, they mount up solid and are well made. In the beginning, I started out with other, less expensive options (MFI for instance) and spent more time messing with them, having to file them to fit specific guns, etc. B&T are the best, and HKParts and RobertRTG are now carrying them. Used to be, you had to buy them from out of the US and have them imported, or just buy used on eBay, etc. Now that B&T has presence in the US, with several distributors, I dont know why anyone would use something else, other than rail welded to the top of the receiver.