The product is 316 L steel. Sold as a pair of earrings. The inner diameter of the earrings is 9 mm - the outer diameter is 12 mm. Bar thickness is 1 mm. Color change is minimized - durability is at the highest level. It will not darken or fade unless exposed to excessive moisture and chemicals. It can be used in the sea and pool. Since it is in the hygienic product group, it is not suitable for exchange or return.