National N351-504 4.5" X 1.5" X 1/8" Corner Plate - Black (1175BC). Used to reinforce 90 degree angles by applying to the side of the angle. Slots for 5/16" Carriage Bolt. Black powder coat finish for improved weather resistance. Warning: The safe working load for this product depends upon the application and fasteners used. In order to reduce the risk of personal injury or property damage, consult with design professionals to determine if this product is appropriate for your application.