I put them on my M66 and M686. The front sight goes into the notch, replacing the red insert, then you Loctite it in place. The rear sight only replaces the blade part of the rear assembly - using a screwdriver, twist the adjustment screw on the old sight until it breaks, the replace the blade with the Mep blade.
Once replaced, they are a 3-dot style, very robust and sturdy looking. Also, the Meps are pretty bright, more so than my other Trijicons.