HLS-12 HEICO Fastening Systems HEICO-LOCK Washers , Manufacturer Part#: HLS-12 , Manufacturer: HEICO Fastening Systems , Brand: HEICO-LOCK Washers , UOM (Inch or Metric): Metric , Material: Steel , Finish: Zinc-Flake Coated , Bolt Size: M12 , Inside Diameter: 13.00mm , Outside Diameter: 19.50mm