I need to make two short fences (3 and 4 feet each). My idea was to use 4x4's for the fence posts. I want to just make pre-fab fence panels that will fasten directly to the face of the posts. i.e. the posts will be hidden behind the panels. I would however like to make the panels removable. I envision those steel hooks on the end of the rails that would slip into metal slots on the 4x4's. I think it seems like a good idea I don't dont know what that hardware is called. Can anyone help?