Approximately 29x9.4x3mm gunmetal plated base metal hinged donut bails for jewelry making. These bails have a 16mm inner diameter, and are easy to open and close. Plated over zinc. Fits up to 3.2-3.6mm chain or cording. For use with 40mm round gemstone donuts up to 6mm thick. Black gunmetal color may range. Once the interlocking loops are strung onto chain or cording, the donut is securely locked.