Aluminum Round Tube, Aluminum, 6061, T6, Round, 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 Heat Treatable, Mechanical Mill, 85 HRF Rockwell Hardness, Standards ASTM B221.