Flat washers are great for adding resistance to your bolts and screws to prevent them from boring into the surface and weakening it. Silicon bronze fasteners have high strength and high corrosion resistance against salt water, acids, salts and organic chemicals. Excellent for marine environment.
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.