Product review (3 stars): Don't repurpose on flexible surfaces.
Plastic is good quality but internal spring is cheap; and pretty weak.  I was repurposing them to hold  some files from sliding back in a milk crate type storage box, and they failed for that purpose because the sides of the crate's sides against were they were wedged were too flexible - in this case an even weaker spring might have helped.  Just a caution of what should be obvious but sadly wasn't to me.