Thank you for viewing. This necklace is inspired by the whale tail, which is said to be a symbol of good luck. It's a type that you put on over your head without removing the clasp, and you can adjust the length after putting it on. It's also stress-free to put on and take off. The material is surgical stainless steel (316L). 316L, 304, and 202, known as surgical stainless steel, are low-allergen materials and are used in medical tools such as scalpels and scissors, as well as high-end watches. It is a special stainless steel with excellent properties such as being rust-resistant, corrosion-resistant, oxidation-resistant, and heat-resistant. Unisex (for both men and women) Size: Free Whale Tail: 25mm x 29mm Material: Cord: PU leather Whale Tail: Surgical stainless steel (316L) Color: Leather: Black Whale Tail: Matte Silver Please feel free to contact us if you have any questions.