Aluminum Infill and Greek Key Castings can be added to staircase and balcony railings, fences and gates. Aluminum infill castings can be added to the top of a railing design to serve as a decorative metal border. Aluminum infills, when added to a fence or gate design, will break up the length of the aluminum pickets for a softer, more decorative appearance. Greek key castings can be welded together to create a geometric/modern appearance on any metalwork design. Choose an aluminum casting to suit your design. There are many styles to choose from and all are double faced.