Finish

Plain

Nothing has been done to this bare metal surface to improve appearance or corrosion resistance, which is very low if the material is steel. Often the surface has been oiled which improves lubricity. This finish is susceptible to rusting and corrosion in exterior environments. This most basic finish can be used when protection is not an issue or indoors.

Grade

5

This grade is from the SAE scale. Made of medium to low carbon steel, it is of medium strength on the grade scale.

8

This grade is part of the SAE classification; it is the minimum standard of the automotive and structural industries, plus it is used in high-temperature applications. Grade 8 is near the high end of the grade scale, although there are higher grades and strengths for more specialized fasteners.

A

This grade is not on the SAE classification, but is similar in strength to Grade 1 or 2 on the SAE scale. This is a low strength grade.

Material

Steel

Steel is the most common fastener material due to its strength properties. Unalloyed steel may be surface treated to enhance corrosion resistance and other desirable properties.