Plate material aluminum alloy, 42 fastener holes, 0.250 in. Nom hole dia. Each hole, 8 attachment holes, 0.218 in. Nom through 0.400 in. Nom dia. X 100 degrees countersunk each hole, 2 rail assemblies spaced 7.375 in. Nom apart, 12 holes 0.630 in. Nom dia. To accomadate 12 retaining rings and stud seats, assembly is part of 3 man seat, medevac system
