I put them into my M&Ps. Simple to install. I watched Randy Lee of APEX on a how to do on YouTube
Much better than the factory trigger, IMHO.
Before hand, I contacted Mas Ayoob and asked him if there'd be a problem with a change in the trigger if the weapon was used in self defense. He wrote back as long as the trigger was within factory specs, it was good to go. It was according to my trigger scale (exception was the completion trigger in my Pro 40, which I wanted to make lighter.)