This specification covers an aluminum alloy in the form of extruded bars, rods, and profiles (shapes) produced with nominal thickness up to 3.000 inch (76.20 mm), inclusive, and having a cross sectional area of 42 square inches (271 square centimeters) maximum and a circumscribing circle diameter (circle size) of 15 inches (38 cm) maximum (see 8.9). See 8.3 for definition of circumscribing circle size.