Steel reinforced concrete plain base panels (sometimes referred to as gravel boards) have a variety of finishes, including a smooth finish or a rock faced finish. These base panels are designed to slot into concrete posts. The slotted posts allow you to slot into your base panel first, followed by your fence panel. The concrete bases are to fit under wooden fences to prevent contact with the ground (rotting) or to keep back soil on different levels. However, they can also be built up on top of one another to form a solid concrete panel fence if this is what you want.