choose recoil rods under glocks only then read the history,R&D, upgrades etc. pictures etc. You have to kind of dig around his site to see all the info.
http://deadbangrecoilrods.com/index.html
i have to say that his 100 percent guarantee makes me consider trying it.
when you watch the video and read the pages on shipping he does come across a little eccentric and yet i find it refreshing. No messing around just straight forward talk.