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 cabinet Made 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 customers since 2017(10 Years Warranty