Aluminum alloy, composition 2024, temper t4, qq-a-250/4 anodize, type i, class 1 per mil-a-8625, 0.150 in. Thk, three 0.280 in. Min0.290 in. Max diameter holes countersunk 0.491 in. Min, 0.507 in. Max diaby 99 degree min, 101 degree max, equally spaced on 2.625 in. Bolt circledia, 0.38 in. Inside corner radius 3 places, 1.69 in. Outside cornerradius 3 places, 1.625 in. Id