Snake 40cm Chain width: Approximately 1.5mm Surgical Stainless Steel 316L What is Stainless Steel? A compound word of "stain" (to get dirty, to rust) + "less" (not). Literally means "hard to rust" and "hard to ionize." An alloy of iron, nickel, cobalt, etc. Although it contains metals that can easily cause metal allergies, it is formulated with improvements to make them rust-resistant, and is attracting attention as a metal that is unlikely to cause allergies. It does not discolor in air and is hard and scratch-resistant, so you can use it with peace of mind. Safe gold color with K18 plating: K18 plating is applied to the surface of the stainless steel. Because of the high purity of gold, it is said to be less likely to cause allergies. It is resistant to rust and discoloration, and the luster lasts a long time.