M6 Thread Style, 16mm long.Square cage nut designed for racks and cabinets with square holes, Mounting your standard rack mountable equipment into a server rack or cabinetMade of top quality carbon steel, black nikel plated. it will not rust in 15 years, Made of top quality carbon steel, black Nikel plated. Nikel is a vital element to make stainless steel, the color of screws and cage nuts are pure Black in dark condition, and a bit of shiny on light conditioin due to light reflection.Includes 60 Cage Nuts, Screws and Washers. Packed in Recyclable box instead of plastic bag.Quality you can count on - Tested by tens of thousands of Amazon customers since 2017(10 Years Warranty）