Shock Cord Retention Loop
$4.00
You can probably come up with plenty of uses for this loop but it's intended to hold the slack on a sling against the side of a rifle during storage or transport.
This is not really necessary for the unpadded slings with their built-in slack retainer; it is intended for use with the wider, padded slings.
Made from 12 inches of 1/8" shock cord.