HLS-1/2 HEICO Fastening Systems HEICO-LOCK Washers , Manufacturer Part#: HLS-1/2 , Manufacturer: HEICO Fastening Systems , Brand: HEICO-LOCK Washers , UOM (Inch or Metric): Inch , Material: Steel , Finish: Zinc-Flake Coated , Bolt Size: 1/2 Inch UNC , Inside Diameter: 0.530 Inch , Outside Diameter: 0.770 Inch