HLS-11 HEICO Fastening Systems HEICO-LOCK Washers , Manufacturer Part#: HLS-11 , Manufacturer: HEICO Fastening Systems , Brand: HEICO-LOCK Washers , UOM (Inch or Metric): Metric , Material: Steel , Finish: Zinc-Flake Coated , Bolt Size: 7/16 Inch UNC (M11) , Inside Diameter: 0.450 Inch (11.40mm) , Outside Diameter: 0.730 Inch (18.50mm)