The maximum size tubing is one inch (25mm) and the maximum wall thickness of for steel tube is .08. Sure enough, the tube I had to bend was at the max limit. Normally tube this large would be bent with a hydraulic press, but after mounting the bender to a work table that was anchored to a wall and then applying every last bit of strength I could muster, I was able to make 90 degree bends in two tube sections. So it was difficult, but smaller tube and thinner tube walls would be much easier. Despite the difficulty the results were good. The bends were smooth and there were no flat spots.