Similar to fiber optic jumpers, tail fibers are classified into single-mode and multimode types, differing in color, wavelength, and transmission distances. The transmission characteristics of most interest are those of attenuation (or loss) and bandwidth. The importance of reducing the attenuation has been. A tail fiber, also known as a fiber optic patch cord, consists of a connector on one end and a cut end of the fiber optic cable core on the other. It often appears in fiber optic terminal boxes. For graded index multimode fibers the core is made with progressively changing. Attenuation is a measure of decay of signal strength or loss of light power that occurs as light pulses propagate through the length of the fiber.