I am very pleased with these style hooks, they generates a strong suction. I got this double hook and single hook version.
The single hook is extends forward 1".
The double hooks extend 3/4" forward.
One of the hooks has been holding my bath rope (several pounds) for a week and has not fallen off so far, the other one works great for cord management because I can attach to the side of my computer case.
This hook works well on non-porus surface. I tried on glass, metal, tiles, and plastic and it worked well. Documentation also says it works on wood, but it did not work well on my teak desk. It has a natural finish which is not totally smooth.
To attach the hook I needed to position the base where I want the hook to be located starting with the hook turned to 3 o'clock position, then turning the hook 90 degrees twisting down (to 6 o'clock position). The part that rotates is the hook (not the base). It forms a rather secure hold.
You can find it on Amazon by following this link.
Ali Julia review ★★★★★