Aluminum Round Tube 6061 Aluminum 6061 T6 Round Tube 12 in Overall Length Length Tolerance +/-0.032 in Outside Diameter 5/16 in Inside Diameter 0.214 in 0.049 in Wall Thickness Wall Thickness Tolerance +/-0.003 in Heat Treatment Tempered Heat Treatable Yes Mechanical Finish Mill F85 Rockwell Hardness Standards ASTM B221