6aluminum alloy, 4.721 in. Od flange, 3.555 in. Min, 3.557 in. Max diameter base, 4.0625 in. Diameter top face, 1.797 in.Min, 1.828 in. Max diameter bore, 0.125 in. By 45.0 degrees both ends of bore, bore and underside of flange 63.0 microinch, balance 125.0 microinch finish