Used it last summer, for a kid at summer camp, by attaching one end to the screw off cap of a water bottle and the other end to the neck of the bottle, like a chain on a canteen lid. Worked like a charm the whole week.

Buttons never come off after they're sewed back on with floss.

Wound around a small rock gathered into a couple of corners of a bandana, space blanket, or lightweight tarp it becomes a makeshift fastener.