sentences:  Typical modern multimode graded-index fibers have 3 dB per kilometre of attenuation (signal loss) at a wavelength of 850 nm, and 1 dB/km at 1300 nm.Singlemode loses 0.35 dB/km at 1310 nm and 0.25 dB/km at 1550 nm.Very high quality singlemode fiber intended for long distance applications is specified at a loss of 0.19 dB/km at 1550 nm.