Stainless steel is an iron-containing alloy made from some of the basic elements found on earth: iron ore, chromium, silicon, nickel, carbon, nitrogen and manganese. The properties of the final metal change depending on varying amounts of these elements. More than 57 stainless steels exist and are sold as standard alloys on the market. Klean Kanteens® are constructed from high-quality, 18/8, food-grade stainless steel. The numbers stand for the percentages of chromium and nickel in the steel, 18% and 8% respectively. Chromium increases the metal's hardness and nickel gives it strength. Together they also make stainless steel highly resistant to stain or rust. Stainless steel is easy to clean, durable, inert and sanitary. That's why it's the material of choice among the food processing, dairy and brewing industries.