Very strong, I'm not an engineer but the construction seems very good. The structural components are made of steel, with the cable management covers being made of plastic. I have been using these for a year or more now, and there have been absolutely zero issues. They handle the weight of my monitors easily (27" monitors) at every angle I've attempted. No sagging in tilt or extension at all.

The only thing that gave me pause was the bright yellow branding spots at the base and the arm, but I can't see the ones on the arm. I could peel the ones on the base off if I wanted, it's a bubble type of emblem stuck into a recess with adhesive. I don't bother, because you can just turn the base away from you when you mount it on your desk, whether with holes in the desk surface, or clamped at an edge (it comes with mounts for both)

It does what I need it to do. I was going to spend much more on a heavy duty set of arms, but they would have required special orders, and I've found I was aiming to overshoot the mark. These are perfect for what I wanted, which was to get my multiple displays up at a more natural height for viewing angle, and free up desk space from monitor stands which had to move with the monitors and took up more space.