Small and elegant ring keys such as these were a Roman innovation. Sometimes they depicted the door for which they were designed to unlock. Furthermore, keys were considered a status symbol because the owner implied that he had valuable assets to protect by wearing them. Such rings are also believed to have symbolised marriage or betrothal, and were worn by Roman brides to signify their role in household management.
Keys and lock bolts account for the most common items of Roman security hardware to survive today. Keys were used mainly for doors, chests, boxes, caskets, cupboards, and padlocks, although they sometimes served ceremonial or decorative purposes, such as matron keys, jewellery items, and votive offerings. Keys such as these were in use from the first century A.D. until the early medieval period.