They do work. I've got a GP100 with those on it. But, you need some hardware. It takes a screw, two "ferrules" (I don't really know what those are, but that's what Midway's website calls them), and a locator pin. It's not hard to install. You just need the right pieces. I got the grip I have with no wood inserts from Midway. I had to order the hardware with it, and each piece was about 3 bucks, I think. I then order inserts off of eBay. If you go the same route I did buying the empty grip, just make sure to order the hardware, too.