Aluminum Square Tube, is an extruded aluminum that is widely used for all types of fabrication projects where lightweight and corrosion resistance is a primary concern – frame work, support columns, gates, fencing, handrails, etc. Aluminum Square Tube has square corners inside and outside, with no weld seam. Available in both 6061-T6 and 6063-T52, with the 6063 square tube being more formable than the stronger grade 6061 square tube. Metals Depot stocks hundreds of sizes of aluminum square tube that you can buy online in ready to ship precut or mill lengths or order just what you need Cut to Size in small or large quantity at wholesale prices.