Material: Safe 316L surgical stainless steel and real opal made, stainless steel is lead and nickel free, good for those who are sensitive to other metals. real opal stone, the colors will changing each time follow the lights. 16G horseshoe earring opal colors: white, pink, green, light blue, purple colors for choose. Size: 8mm hoop inner diameter tiny 3mm opal stone, tight four prong-set part is securely lnlaid and won't loose easily. Can be used for: the curved bar gauge is 16g(1.3mm thickness), pefect for cartilage piercing, face nose septum rings, labret stud, lip stud, tragus, eyebrow, nipple, and so on.