8plate-aluminum alloy sheet 6061-t6 per qq-a-250/11 - plate and block-aluminum alloy plate 6061-t6 per qq-a-250/11, anodize per mil-a-8625 type 2 class 2 color black no.37038 per fed-std-595 /spacer-passivate qq-p-35 type 3 with exception to par. 4.3