It's an Ed Brown ambi safety. Complete PITA to install. Aside from fitting the blocking lug to the sear, I also had to fit both sides to the frame as well as bevel the edge of the right side because it is left kinda sharp and cuts into my hand (left handed)....I think I'll have to do some more though because it is still a bit uncomfortable.
I was actually looking at those sights, mainly just the front ones. I want to run something like that and a Harrison retro rear but i'm saving the change until I get the gun refinished later down the road. I wanna have a go at dehorning the edges of the slide/frame and maybe put in a fitted beavertail.
I like your grip safety...they don't make em anymore right?