Bolt level, and the meaning of bolt levelClass 8.8 hexagon head bolt

GB 819-85: Cross Slot Countersunk Head Screw

GB/T 819.1-2000: “Cross recessed countersunk head screws Part 1: Steel Grade 4.8”

Nuts and bolts are common mechanical connectors, widely used in all walks of life, and their main role is to connect two or more parts together to complete the assembly or maintenance of the machine.