It's the Miculek grips and I really liked them on the squareframe 686 that I've had the longest. I got the grips for the .22 before I got the revolver itself, but for some reason they didn't work quite as good as the ones on the 686. But after a little work on the area where the middle finger grips they too now feels good.
For me these grips moves around less in my hand, strange as it may sound. I can shoot SA single handedly without the revolver ending up in a strange grip, and DA also works good (though I don't practise anywhere near enough).