304 stainless steel has good corrosion resistance in a bad environment like high temperature, cold weather, and high humidity areas. They have superior rust resistance and the excellent of oxidation resistance. These washers are very strong and are great for both indoor and outdoor use. The larger outside diameter perfect for applications that require a larger amount of pressure distribution such as drywall, fencing, mounting fixtures, and sheet metal. NOTE: Please check the size carefully before purchasing. Warning: the product are small parts, keep away from children and kids.