Design Pine:
An engineered timber impregnated with H3 (organic preservation system).
This means you get a knot and blemish free timber which will last 25+ years in the harsh Australian environment.
Design Pine is excellent for gates that are enclosed, or looking to have a sleek painted finish. 
It comes pre primed making painting a breeze leaving you with a superior finish.
Not only will Design Pine last 25+ years if maintained correctly, it is very lightweight for its strength, which can be important for larger gates.