This rear sight has a concealed dovetail under a front and rear skirt. It will hide a rough looking slot on a 13/16” or 7/8” octagon barrel. The dovetail is about .385” as cast, it will clean up to a standard .375” dovetail. The base is .550” wide. Height from the bottom of the dovetail to the top of the sight notch is 0.39".