Back Home / Fasteners / Washers / FLAT WASHER USS ZINC 1″ THRU HARDENED FLAT WASHER USS ZINC 1″ THRU HARDENED SKU: 8FW1 Categories: Fasteners, Washers Used to improve stress distribution, and to span large holes. USS PATTERN. Made from heat treated thru-hardened steel, zinc yellow. Outside Diameter: 2-1/2″ Inside Diameter: 1-1/16″ Case Quantity: 25 Log In For Pricing