alum alloy A380, ams 4291; yellow chemical film per mil-c-5541; 3.830 in. od; 1.167 in. nom lg one side; 0.891 in. nom lg other side; three holes 0.200/0.210 in. dia, 2.336 in. c to c, one hole 8-32-unc-2b thd, 0.375 in. deep; three holes 8-32-unc-2b thd, 0.313 in. deep, 1.915 in. nom c to c