HLS-16 HEICO Fastening Systems HEICO-LOCK Washers , Manufacturer Part#: HLS-16 , Manufacturer: HEICO Fastening Systems , Brand: HEICO-LOCK Washers , UOM (Inch or Metric): Metric , Material: Steel , Finish: Zinc-Flake Coated , Bolt Size: 5/8 Inch UNC (M16) , Inside Diameter: 0.670 Inch (17.00mm) , Outside Diameter: 1.000 Inch (25.40mm)