Material: sterling silver 925 Size: about 4mm Choose 925 material, the bracelet is not easy to change Please use a long strip of paper and measure the size with your wrist (do not loose too tight, then select S (19.9cm or less) or M (20cm or more) by number. After placing your order, please contact the designer to discuss the bracelet size. Maintenance method When sterling silver jewelry is worn, it will be "moisturized" by the body's natural oil, so the more it shines, the brighter it will be. When not wearing, please store it in a jewelry box or a zipper bag to isolate air contact as much as possible. When the sterling silver jewelry turns yellow and black, you can wipe it with a silver cloth. The silver cloth will turn black, but don't wash it!