"ARMOR PLATE MATERIAL STEEL, WROUGHT HIGH-HARDNESS, SPEC. MIL-A-46100, OVERALL THICKNESS 0.210 INCHES. ITEM IS DIFFERENTIATED FROM PART NUMBER 12350772 (NSN 2590-01-234-1904) BY A 7.00 INCH CONCAVE INDENT IN THE ITEM. ITEM HAS THREE SLOTS FOR MOUNTING"