Where would you normally use treated timber fence post caps?
On top of a 90 x 90mm fence post to dress it up.

What is it made out of?
Plantation grown Radiata Pine that has been H3 treated (suitable for above ground use).

How should you finish it?
A water based primer/undercoat is not a necessity (although it wouldn’t hurt), but at least 2 coats of the final colour is a must.
Leaving it unfinished, oiling it or using a clear lacquer is not recommended.
Speak to your local paint retailer for more info.