PRODUCT SPECIFICATIONSPart #: 0000-113592Fastener Type: Flat Washer Narrow Pattern Through Hardened - USASize Description: M16Diameter/Nominal Size: M16*Inside Diameter: 17mm-17.27mmOutside Diameter: 27.48mm-28mmThickness: 2.3mm-2.27mmSystem of Measurement: MetricProperty Class: 200HVMaterial: Medium Carbon SteelFinish: Zinc PlatedUsed with: Bolts/Screws up to Class 12.9Average Piece Weight: 0.0286000 lbs.Country of Manufacture: United States*Washer Sizing: Washer sizes are nominal (sized for the bolt that the washer will fit). Actual inside diameter is almost always larger than stated size. Please see the Inside Diameter spec in the table above, if available.Washers are thin disk-shaped plates with a hole that is used to distribute the load of a threaded fastener such as a bolt or nut; often have an outer diameter (OD) about twice their inner diameter (ID), but this can vary based upon the washer. Washers come in many different varieties; flat washers, split lock washers, toothed lock washers, beveled washers in both steel and iron, etc.