National Catalog 1217BC heavy duty square corner brace. Used for reinforcing 90 Deg. angles by applying to the inside or outside of the corner. Slots for 5/16 In. carriage bolt. Square shape and multiple bolt slots per side provide greater area of stability for wider pieces of building materials. Chamfered corners provide decorative look. 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.