Mount these lightweight half rounds on flat surfaces to reinforce frames and structures. Carbon fiber is often used in place of aluminum because it weighs less but is almost as rigid. These half rounds have fibers that run in one direction, making them strongest in the direction of the fibers. They resist bending across the fibers but will splinter and separate like string cheese when bent along the length of the fiber. Carbon fiber is known for its use in the aerospace industry where a balance of weight and strength is critical.