o-ring
Any clothing or accessories that have an O-shaped ring through which parts of a garment can pass and then connect together. Any types of clothes that aren't implicated here can just use this tag as a placeholder, rather than creating new tags for every type of o-ring clothing.
For the time being, "o-ring" also covers all other loop shapes, such as ovals, rectangles or any thing else containing a hole. For hearts, use heart o-ring.