★Material: Made of alloy steel, good hardness, low temperature strength and corrosion resistant. ★Size: 9 Sizes of the most commonly used flat washers, M2 M2.5 M3 M4 M5 M6 M8 M10 M12. ★Quantity: It contains 9 sizes totally 684pcs, each size comes in a little poly bag organized in a little compartmentalized box. Perfect for having around the house and doing small projects. ★Functions: Flat washers are mainly used to reduce pressure and friction, prevent leakage, isolate, loosening or disperse pressure. Black Zinc Plated Alloy with rust resistan