Thank you for viewing. This is a surgical stainless steel (304) bracelet. Surgical stainless steels such as 316L, 304, and 202 are low-allergen materials and are used in medical tools like scalpels and scissors, as well as in high-end watches. They are special stainless steels with excellent properties, such as being rust-resistant and highly resistant to corrosion, oxidation, and heat. Unisex (for both men and women) Sizes: Wrist circumference: S size: 15cm, M size: 17cm, L size: 19cm, LL size: 21cm Please specify your size after purchase. If no size is specified, we will send a size M. Thank you for your understanding. (Example: If your wrist circumference is between 16.5cm and 17.5cm, size M will fit.) Chain width: 7mm, 10mm Material: Surgical stainless steel (304) Color: Silver Please feel free to ask any questions.