Doler-zinc no. 3, sae alloy-903, half round shape, 4.000 in. @radius, 1.156 in. Thk, four 0.406 in. Diameter holes around outer face, two @inner holes @spaced 2.375 in. C to c and two outer holes spaced 6.000 in. C to c, two 0.344 in. Holes drilled in top end, 6.000 in. C to c