Yep, cut it out of an old brass data plate that was .130" thick. Thinned it a bit and stuck it in a .125" slot and then milled it to .100 thick. Shows up good in the .140 rear sight notch. The mate to this one (you need pairs of everything for CAS) had the .140 notch as Ruger now makes that standard. This one was a little older and had to be opened to .140.