I used the mini gating gun shroud, so in order to do the halo inside you have to completely trim out the "screw in posts" which hold the shroud in place the the projector with 4 screws. I did that and going to have to hold it on with jb weld/epoxy now. I believe it was an 80mm on the inside and a 70mm on the front of them. Probably easier with a larger shroud , and might change it up sometime because that's how I am