Sawn timber, pressure treated with a bronze finish.
Most commonly used to support your fence panel above ground level to preserve the condition of the timber and extend the life of your panel.
Gravel boards, (or kick boards as they're also called) are most commonly used to raise your timber fence panels or boards off the ground to extend the lifespan of your fence by preventing moisture damage from the damp or wet ground.
Remember: You must have your fencing panel raised off the ground to validate your warranty.
If using with timber posts, you will need to use gravel board brackets to hold in place.