SAE AMS4337C PDF
This specification covers an aluminum alloy in the form of extruded profiles (shapes) 0.500 to 1.500 inch (12.7 to 38.1 mm), inclusive, in nominal thickness, and having a maximum cross-sectional area of 20 square inches (129 cm2) and a maximum circle size of 10 inches (254 mm) (see 8.7).