HLS-36 HEICO Fastening Systems HEICO-LOCK Washers , Manufacturer Part#: HLS-36 , Manufacturer: HEICO Fastening Systems , Brand: HEICO-LOCK Washers , UOM (Inch or Metric): Metric , Material: Steel , Finish: Zinc-Flake Coated , Bolt Size: 1-3/8 Inch UNC (M36) , Inside Diameter: 1.470 Inch (37.40mm) , Outside Diameter: 2.170 Inch (55.00mm)