Flat washers are great for adding resistance to your bolts and screws to prevent them from boring into the surface and weakening it. Zinc plated fasteners have good corrosion resistant qualities and are a good choice for indoor, outdoor and industrial applications. Metric washer hardness is represented by the HV number or Vickers hardness. Use 200 HV washers with class 8.8 screws, bolts and class 8 nuts. 300 HV washers should be used with class 10.9 screws, bolts and class 10 nuts.
If there is an "(S)" in the part name, it indicates that it has a smaller O.D, compared to the "(L)" which indicates that it has a larger O.D
For the product numbers that are sold by weight, 5lbs or 40lbs the individual pieces that are contained within the package are approximate due to manufacturers making some flat washers/lock washers slightly thicker, or thinner.