Specifies an aluminium in the form of drawn, round seamless tubing 0.500 inch (12.70 mm) and over in OD with wall thickness of 0.029 to 0.500 inch (0.74 to 12.70 mm). Typically used for structures needing good fusion weldability and a combination of good strength and resistance to stress-corrosion cracking, but usage is not limited to such applications.