ND usually stands for Non Destructive and is usually followed by the word 'Testing' when used to describe material analysis without destroying the material in question.
In my case it stands for hooks that will affix to the walls of Lynda's cabin without the need to affix a fastener.
The walls of Lynda's cabin at work are sheet metal partitions covered with fabric. Lynda had been issued strict instructions by the building manager that no hooks of any sort would be allowed to be affixed to the panel for the purpose of hanging her frames.
I sorted through the box of magnets that I had culled earlier and isolated those that had some sort of threaded hole within the body. Using the screws that I had saved, I affixed hooks (I used the Hilti Fix hooks that are not normally sold in North America) to the magnets.
They are super strong and should hold almost anything. They're not that good looking, but it does not really matter as they will be hidden by the frames.
The hooks affixed to my fridge
Another angle showing the profile of the hooks
These hooks are part of the Hilti-Fix system that is sold in the
Middle East and Europe and are meant for fixing into concrete walls