I have no idea what these are intended for, but I bought them for an attempted experiment to use them as "clear" O-rings for fishing wacky-rigged stick-baits for bass. I had hope that the material would be pure silicon(stretchy and fairly opaque) to avoid creating an unnatural color-contrast between this ring and the artificial bait(Senko.) Warning: This material becomes more visible when it stretches and turns a prominent white-color, thereby, defeating the purpose of buying it. I'm just letting other anglers know that this is not an ideal substitute for standard O-rings for wacky-rigging.