Galvanised

Similar process as Zinc plating but a thicker layer is applied.  Has a higher corrosive resistance than zinc.  Commonly used in agriculture and marine industries.

Galvanization or galvanizing 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 the parts are submerged in a bath of molten zinc

Galvanizing protects the underlying iron or steel in the following main ways:

• The zinc coating, when intact, prevents corrosive substances from reaching the underlying steel or iron.
• The zinc protects iron by corroding first. 
• In the event the underlying metal becomes exposed, protection can continue as long as there is zinc close enough to be electrically coupled. After all of the zinc in the immediate area is consumed, localized corrosion of the base metal can occur.