GB9074 class portfolio bolt, high strength bolts

Outer hexagonal screws means with cross slot outside hexagon bolt flat pad combination screw. Hereinafter referred to as composite bolt. Or outer hexagonal screws, the label for GB9074.13. There is another common outer hexagonal screws, GB9074.13-1988 refers to the outer hexagonal screws of the specifications of the standard is stipulated by 1988. It is also called cross trough recesses hex bolt, spring washer peace washer assemblies. The label for GB9074.17. Refers to the outer hexagonal screw cutting edges. That is not outer hexagon bolt with a cross. Let's look at portfolios under the bolt GB9074.13 size figure, more can understand cross slot combination hexagonal head bolt of some basic professional knowledge.
GB9074 class portfolio bolt, high strength bolts