I use the "baby" stretchy ponytail holders. Just the right size for bobbins.
Another use for the ring: if you have a refrigerator/freezer that you need to shut down, put the ring through the freezer door and fridge door handles. Then prop the door open. The ring makes both doors into one unit. I block my fridge door open using a trash bucket and because the doors are "tied" together, there is no chance that the freezer door will close by accident. I've been doing this for years and it works well.