316L steel, or surgical steel as it is also called, is the material in which most of all piercing jewelry is made. It contains about 17% chromium, 12% nickel and 2.2% molybdenum, but it is so tightly bound in the metal that less than 0.1 millionth of a gram of nickel is emitted per cm2 and week. It is so small that 316L complies with EU directives for products that come into close and long-term contact with the skin. The limit value is 0.5 millionths of a gram / cm2 / week. "Ordinary" nickel allergy sufferers can usually wear 316L surgical steel, but if you are very sensitive or worried, you should choose titanium instead.