What a great idea - and a shout out to Bennett for the suggestion. These are "ring-resizers" for making your too-big ring fit. Or, for making the only ring that goes over your swollen knuckles not slither around your finger once you get it on.
These are a plastic coil that you spiral around the shank of your ring until it is a comfortable fit again. Trim off what you don't need, and save it for the next ring. Two sizes in the package, small and large, to fit whatever size ring shank you have (thin or chunky). Unobtrusive. Easily removed without damaging the ring. Great idea. Two of each size in the package - you can resize a lot of rings with this.
3.5 / 5mm x 100mm By the pack of 4.