Buy 40mm x 40mm x 3mm mild steel box section in a range of different lengths with metals4U. We have standard 3 metre and 6 metre pricing options available, with a free custom-cutting service for anyone looking for more specific measurements. This 40mm x 40mm x 3mm mild steel box section is E220 grade and comes with a mill finish. You can find more product information and submit any questions for our team below. This 40mm x 40mm x 3mm mild steel box section is fit for various applications, and if you order before 2pm, you can rely on same-day dispatch to help you finish the job quickly.