Silver 15mm Round Hoop EarringsSilver Hoop Earrings These sterling silver round hoop earrings measure 15mm in diameter. The material is sterling silver, which is composed of 92. 5% pure silver, giving the earrings a bright and durable quality. Each earring is fastened with a saddle back closure. This mechanism works with a hinged post that clicks securely into a catch on the back, ensuring they are easy to put on and comfortable to wear.