Cylinder Head Bolt Special Bolt Hexagon Drive The Thread

Cylinder head bolt also called round or column bolt, the head without any drive and the hexagon socket drive on the end of the thread. Cylinder head bolt mostly used on precision equipment. Ever Hardware provides custom-made fasteners and customizable packaging.
The hex socket screw drive has a hexagonal recess and may be driven by a hex wrench, also known as an Allen wrench, Allen key, hex key, or inbus as well as by a hex screwdriver (also known as a hex driver) or bit. Tamper-resistant versions with a pin in the recess are available.

Galvanization, or galvanisation, (or galvanizing as it is most commonly called in that industry), is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc. Galvanizing protects in three ways:
It forms a coating of zinc which, when intact, prevents corrosive substances from reaching the underlying steel or iron.
The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc. The zinc protects its base metal by corroding before iron. For better results, the application of chromates over zinc is also seen as an industrial trend.