I have Trijicon HD sights on my many M&P pistols and want to install them on the Shield 45 I picked up a couple weeks ago. I sent Trijicon an email to verify that model SA139 for the 9 and 40 would fit the 45 and this was thier reply: "Thank you for your interest in our Trijicon HD sights, we have been provided a definitive Yes from Smith and Wesson that the .45 caliber Shield shares the same cut and designed sight height as the other versions."