Grade 8 USS Thick Flat Washer Zinc Plated 5/16

This Grade 8 USS thick flat washer is designed for 5/16-inch bolts and made from through-hardened alloy steel for high tensile strength. Featuring a yellow zinc chromate plating for moderate corrosion resistance, it meets ASME B18.21.1 dimensional and mechanical standards. Its wider bearing surface helps distribute loads evenly, minimize joint damage, and prevent loosening under vibration.