Flat washers are great for adding resistance to your bolts and screws to prevent them from boring into the surface and weakening it. 316 stainless steel fasteners have excellent outdoor, salt water, chemical resistance and may be mildly magnetic. The best choice for all marine applications and outdoor projects.
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.