I bought several of the Cap-retainers many years ago (at a Gander Mountain, I think). Ever since that time, one has been on my sun cap (with a very wide brim) ; and has preserved it for me so many times. I’ve given several away, when people have commented on how great mine was.
They’ve also kept grandchildren’s sweaters and jackets from falling off and getting lost; and kept my canvas bags together on outings, as well as lots of other uses. That’s why I just bought a bunch more. They are made well; and are so handy to have around!