In fibers, trilobal is a cross-section shape with three distinct sides. The shape is advantageous for optical reflective properties and is used in textile fibers. Silk fibers' rounded edges and triangular cross section contribute to their luster ; in some cases, synthetic fibers are manufactured to mimic this trilobal shape to give them a silk-like appearance. Filaments with a round cross section have less brilliance than trilobal filaments.