12in 300mm Dished Concrete Gravel Board. Enhance the longevity of your wooden fence panels with our concrete posts and gravel boards. When poorly maintained, Concrete posts and gravel boards offer the best protection against the elements and are proven to last longer than their timber counterparts. Concrete gravel boards isolate your panels from ground contact which significantly reduces the chances of them being affected by water damage. Concrete fence posts remove the need for nails, brackets and fixings and will provide highly robust support to your fence panels.