All these names refer to wire (or other steel products) that has been galvanised in an alloy of Zinc and aluminium as opposed to normal galvanising that is just zinc. We will refer to it as a zinc-al coating. The alloy is typically 95% zinc and 5% aluminium (Zn95Al5), but variations up to 20% aluminium have been made.
While traditional galvanised coatings deliver a good level of service life, zinc-al has been shown to offer superior corrosion resistance compared to its zinc-coated steel counterpart. In addition, 5% aluminium can double life, and 10% increase life four-fold (in salt-spray tests).
Sometimes the name will be followed by the term “class A”. Class A refers to the zinc/aluminium coating thickness as detailed in BS EN 10244-2. This thickness varies with wire diameter, but as a typical example class A on 4mm is 275g/m2. Zinc-al could also be supplied as class D with a much thinner coating, but generally, as a premium product, it is class A.