I have the Williams rear sight t,hat fits the scope holes and a fiber optic bead on the front of my 1974 vintage carbine. I believe I used a .250 bead on one of the Williams riser blocks, also .250, for the set up. I would have to check my records, but I think that was it. The shorter bead on the riser block gave a more solid, less prone to damage front sight. I took this off for a while and tried a 1.5X4.5 scope, but it shot better with the peep. I tried different diameter peeps and settled on a mid sized one, I think .095. For hog hunting in close quarters, I use a.125, which is almost liike a ghost ring. I like the WGRS sight because it is more compact and streamlined than the 5D.