Unlike a flange, a freely rotating washer disperses pressure across a larger surface area, protecting the surface of your material. These alloy steel screws are more robust than Grade 8 steel screws, with a tensile strength of 170,000 psi. In arid conditions, their black-oxide coating offers a moderate level of corrosion protection. All are made in accordance with ASTM A574 and some additionally fulfill ASME B18.3 standards for dimensions and material quality. Under the head, the length is measured.

If you are unsure of the threads per inch, go with screws with coarse threads, which are the industry norm.