Get 5P4116 C-Brand WASHER At Wholesale Prices, obtain heavy-duty parts from the biggest dealer and supplier.Specifications:"Material: HARDENED STEEL Washer Type: FLAT WASHER Fits Bolt Sizes (in): 5/16 Material Description: Hardened Steel Coating: Zinc flake offers medium to high corrosion protection and repeatable assembly performance via built in lubrication. Salt spray resistance of 720 hours to red rust. Coating color - black (M12 and smaller), grey (larger than M12). Inner Diameter (in): 0.346 Outer Diameter (in): 0.807 Thickness (in): 0.079 Hardened: Yes Finish Notes: Caterpillar is changing from Zinc Plating to a Zinc Flake finish for many washers. The new coating improves corrosion protection to 720 hours. Until stock of the current finish is depleted, you may receive either finish due to the exhaust process. Finish: Zinc Flake"