Hypoallergenic Bioceramics Zirconia Ceramic Square Stud Earrings, No Fading and Nickel Free, BlackSize: about 0.16 inch(4mm) wide, 0.16 inch(4mm) long.Earrings are made of zirconia ceramics which is a widely used biomaterial in medicine. They are nickel free and non-allergenic, perfect for sensitive ears. With exceptional stability, they resist fading and tarnishing, ensuring a durable and shiny accessory. They are washable jewelry for everyday wear.