These stretchy and size-inclusive rings are made of glass and plastic seed beads which form a daisy chain. They are made with crystal elastic string and the knot is secured with super glue to be sure that it doesn't come undone. These rings are extremely durable! I have had them last years for both myself and customers without breaking. Sizing is approximate and based on US size: Small: Ring size 5-8 Large: Ring size 8-11 Care: These are not made of metal so should not tarnish on your fingers, however, avoid contact with hand sanitizer to ensure that the colors of the beads stay the same.