Back Home / Fasteners / Washers / FLAT WASHER SAE ZINC #4 FLAT WASHER SAE ZINC #4 SKU: SFW4 Categories: Fasteners, Washers Used to improve stress distribution, and to span large holes. SAE PATTERN. Made from low carbon steel, zinc plated. Outside Diameter: 5/16″ Inside Diameter: 1/8″ Case Quantity: 100 Log In For Pricing