The Outer Impact adapter plate fits into the dovetail slot of the rear sight. What makes the OI different from the other dovetail slot adapters is the OI unit is made to fit the slide so it can't move. Unlike the other dovetail mounts I've seen that are attached only by screws, this form-fitting design uses the slide to lock it in place.
After about 200 rds of both FMJs and JHPs, it was solid, no screws were loose, and the POI remained the same.
The adapter plate will accept most optic patterns including RMS and RMR. I've attached the mounting instructions so you can see how easy it is to install
https://outerimpact.com/shop/?_product_categories=mounting-platformsTwo points of note that some will see as a negative, though it wasn't for me.
1. The rear sight is completely removed so there is no co-witnessing. As an aside, the P-01 rear sight was hydraulically installed and no matter what I tried to remove it (yes, I did remove the rear sight screw) using a sight pusher and then a big hammer and punches, it didn't budge. I needed to use my Foredom Rotary tool with a metal cutoff wheel to get it out and took about 5 minutes of careful cutting. Most rear sights won't need this action.
2. The Green Dot sets above the bore axis higher than would a milled cutout on the slide. This too wasn't a problem for me. My green dot was easily adjusted using a bore laser at home and then a final adjustment on the range for a 10-yard POA. It required no adjustment in finding the dot as my regular EDCs have green dots.
For a cost of $60, I have a way to mount an optic on any pistol without milling. Well worth it.