Back Home / Fasteners / Washers / LOCK WASHER INTERNAL ZINC 5/16″ INTERNAL TOOTHED LOCK WASHER INTERNAL ZINC 5/16″ INTERNAL TOOTHED SKU: ILW56 Categories: Fasteners, Washers A hardened circular washer with twisted prongs or teeth which extend inward from the inside edge of the washer. This style is preferred when finished appearance is crucial and the teeth must be hidden under the head of the screw Made from spring steel, zinc plated. Rockwell Hardness: C40-50. Inside Diameter: Min .320 Max .332 Outside Diameter: Min .594 Max .610 Thickness: Min .028 Max .034 Case Quantity: 100 Log In For Pricing