Any premises, area or piece or parcel of land licensed and used as a junk yard shall have not more than two entrances and two exits, each of which shall not exceed 15 feet in width at the perimeter of the premises. Such premises, areas, pieces or parcels of land shall be enclosed with either a solid nontransparent wall or mob or link-weave steel wire or combination thereof with a minimum height of seven feet from the ground level excepting for entrances and exits. The fence or wall shall not contain any poster or advertising of any kind excepting one sign of the licensee not exceeding 100 square feet in size.