The Afinia cardboard spools don't have any locking features to hold on to, so I was using "universal" filament clips that clipped onto two pieces of filament.  However, many of those were just too loose, and bumping the spool would cause it to unravel.  This just holds firmly onto the edge, and I haven't had any slippage.I know there are many options for filament clips, but I like this one for the cardboard Afinia spools.