Material: SOFT STEEL Washer Type: Flat Outside Diameter (mm): 29 Inside Diameter (mm): 17 Fits Bolt Sizes (mm): M5 Thickness (mm): 3 Material Description: Soft Steel Coating: Zinc Phosphate + Oil offers corrosion protection up to the point of assembly (recommend painting for external applications). Salt spray resistance of 72 hours to red rust. Coating color - dark grey to black. Inner Diameter (mm): 5.3 Outer Diameter (mm): 25