I think it was Dysan that first showed up with
reinforcing ring kits
Probably, "Grabettes."
Then why was is it that DD media bought well after HD
media was available, in use, and the norm still had the reinforced ring? Tradition?
You might be putting it in an old drive. It was also available without, I had several
thousand without reinforcements from Verbatim, bought in bulk bags.
Thanks,
Jonathan