Chums® slip-fit retainer

Utah, Chums has been making tried-and-true outdoor gear since 1983, when founder Mike Taggett made retainers by hand, in an effort to prevent his fellow adventurers from losing their sunglasses in the Colorado River. These are constructed in nylon rope, which means they're reliably strong and durable, and will outlast any adventure. They also float, of course, and they're adjustable too.