Fence brackets are unique to wrought iron fences and often used to hold the fencing components to the posts. These slide over the rails, are set against the posts and are often then secured with a self-tapping screw to hold everything together. Aluminium fencing does not use brackets. Instead, rails are slid into punches in an aluminium post and then a self-tapping screw is driven through the post and into a rail inside it in order to secure everything.