Valuminum alloy, 6061, temper 6; 2.000 in.Dia; 0.250 in.Thick; used on: projectile 5 inch 54 caliber; bl and p, mk 109 mod 0; he-am, ex 86 mod 0; he-ir, mk 84 mod 1; he-ir, mk 84 mod 0; he-pd/d, mk 83 mod 0; he-mt/pd, mk 82 mod 0; he-cvt, ex 81 mod 0