la gg&g (da non confondere con la g&g, dato che questa e' un'azienda americana che produce parti e accessori per armi vere) ha realizzato alcune varianti di anelli per cinghie da montare sui fucili colt:


the newly redesigned agency rear sling adapter for collapsible stocks offers the end user a more consistent fit than our earlier version. recently some of the recoil tubes being produced are smaller in diameter than the originals. with our new design securely fastening onto the castle lock nut, various size recoil tubes are no longer an issue.

piu' info -> link