High Quality Material: The lock washer is made of manganese steel, with a smooth surface, no burrs, with a black oxide layer, corrosion resistance and rust resistance. 7 Sizes: This box of lock washers provides all the different sizes of gaskets you may need to use. Including 7 sizes M3 M4 M5 M6 M8 M10 M12. Convenient Storage Box: Washers of different sizes can be well sorted in a transparent plastic box with separate compartments for easy storage and easy picking of the required size. Features: Star-shaped lock washers can be used in bearings, exerting spring force between the head of the fastener and the substrate, creating greater resistance to friction and rotation. Wide Range of Applications: It is a good choice for many occasions such as industry, garden, home, garage, workshop, car repair and DIY projects. Products include: M3*9 (60pcs), M4*12 (60pcs), M5*12 (60pcs), M6*14 (50pcs), M8*18 (50pcs), M10*20 (40pcs), M12*25 (20pcs).