High quality material: The lock washer is made of 65 manganese steel, with smooth surface, no burrs, black oxide layer, resistant to wear and tear.corrosion andrust 8 Sizes: This box of lock washers provides all the different sizes of washers you might need to use.Includes 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 to apply spring force between the fastener head and the base material, whichincreases friction and resistance to damage.the rotation Wide range of applications: It is a good choice for many occasions such as industry, gardens, homes, garages, workshops, auto repairs, DIY projects, etc.