Spool unravel protector

This Thing will be featured on the 3D Printing Today Podcast, Episode 86; threedprintingtoday.libsyn.com.
My favorite filament, Prototype Supply, comes on superior taller, thinner spools. These have less of a curving influence on the filament towards the end of the spool and are less likely to tangle from cross overs. However, when new they unravel way too easily when mounted in an overhead manner. This unraveling can cause a serious tangle and jam. So I made this to prevent that from happenin