Aluminum Square Tube 6061 Aluminum 6061 T6 Square 12 in Overall Length 2 1/2 in Inside Width 2 1/2 in Inside Height 3 in Outside Width 3 in Outside Height 0.25 in Wall Thickness Wall Thickness Tolerance +/-0.011 in Fabrication Extruded Heat Treatment Tempered Heat Treatable Yes Mechanical Finish Mill Yield Strength 40 000 psi Tensile Strength 45 000 psi 95 Brinell Hardness B60 Rockwell Hardness Includes Material Certificate Yes Standards ASTM B221