904L Stainless Steel is a highly alloyed austenitic stainless steel. It contains approximately 19-23% chromium, 24-26% nickel, 4-5% molybdenum, and 1-2% copper, along with smaller amounts of other elements. Rolex, for example, has been using 904l stainless steel across their watch collections due to its higher pitting resistance equivalent number (PREN) than any other stainless steel grades.