Hi @Sunderland,
A warm welcome to the Bunnings Workshop community and thank you for your question about attaching 19mm timbers to a metal framed garden gate.
These Zenith 8G x 30mm Galvanised Countersunk Rib Head Metal Screws are a good option for your gate.
The countersunk head will allow the screw to sit flush with the surface of the timber so you will get a nice clean finish.
Let me know what you think.
Jacob
