I had a previous device like this that was made with a metal S and two wooden knobs, one on each end. That one seemed to be higher quality and gave me better point massage on my back. I didn't bring it on this trip, and I had some tight spots on my back so I ordered this.
This one is made out of molded plastic. There's a seam that runs the entire length of the thing all around. That seam is not comfortable. It sticks out and is fairly sharp. I used a nail file to try to file it down at the tips of the knobs.
Even with that, I feel the knobs are too small and sharp. The other one had slightly larger, perfectly spherical knobs, which I prefer.
There are a lot of knobs on this thing. I can't figure out what they all do.
Nevertheless, it's better than nothing.