This is a zip-tie holder that gets a magnet glued into it. The dimensions of the magnet are .75" diameter x .187" thick. Please feel free to mess with it as much as you want. I needed these for a non-invasive wiring harness and couldn't find anything similar for less than CAD$36/pack of 10! Ridiculous!
*I am SURE that this EXACT item has been made before by someone else, but I'll be damned if I can find it!