Flat washers are great for adding resistance to your bolts and screws to prevent them from boring into the surface and weakening it. Used behind a nut or screw head to distribute load and to prevent material from buckling or screw pull-through. Washer sizes are specified by the bolt or screw diameter and should be matched to ensure proper fit. Bare finish fasteners have low corrosion resistance and are a good choice for indoor and industrial applications.
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.