Structural Tube Square Tube – Heavy Wall Material: 304/304L, 316/316L, 409 Specification: ASTM A554 (EN 10219-2) Finish: DOM, 180 Grit Rectangular Tube – Heavy Wall Material: 304/304L, 316/316L, 409 Specification: ASTM A554 (EN 10219-2) Finish: DOM, 180 Grit