OK, the cases I use are closer to 3mm but I understand what you mean.
Hmmm....
So, obviously intended to be *hidden*/unobtrusive. Which, of course, suggests some nefarious intent...
I had a rent-a-cop approach me at a mall and politely *demand* that I remove my bandana from my head: "guys in the local gangs use them to signal their gang affiliation" (recall my comments about my actual age, graying hair, etc.??) I just stared in disbelief replying, "yeah, and I'm told the girls that run with them all wear BRAS..." -- but, he wasn't quick enough to understand the reference.
I figured if they have a bad enough problem with gangs, I don't need to shop there -- and departed!
[I should go back and see if they've taken my suggestion and implemented a strict NO BRAS policy in the years since then!! :-/ ]