Hexagon bolts are divided into ordinary and high-strength bolts according to their strength levels. Ordinary hexagonal bolts refer to grade 4.8, while high-strength hexagonal bolts refer to grades 8.8 and above, including grades 10.9 and 12.9. Grade 12.9 hex socket bolts generally refer to black hex socket cup head screws with knurled and naturally colored oil.

Hexagon bolts are classified according to the hardness, tensile strength, yield strength, etc. of the screw wire, which is the grade of the hexagon bolt and what grade the hexagon bolt is. Different grades of hexagonal bolts are required for different product materials, and all hexagonal bolts have the following grades: