Package Included: 10pcs Thread Length: 3/4" (not including head height) , Head Height : 0.37 inch , Head Diameter: 0.56 inch . Thread Diameter: 3/8" (0.375") , Thread Pitch:16 (0.0625") . Allen Hex Drive Size: 5/16" (0.3125") Material: Alloy Steel 12.9 Grade Black Oxide Material: Alloy Steel 12.9 Grade Black Oxide
Size: thread diameter d* thread length L (not including head height)

Allen Hex Socket Head Screw Bolt You can could see them around because they are widely used in a variety of industries such as construction, manufacturing, engineering, assembling landlords repairmen and so on.