UNC Group SpeedaLite Single-mode fiber optic cables are fully tested and gauranteed for the lifetime. The 9 refers to the actual diameter size of the core itself - measured in microns. Single-mode fiber optic cable cable is recommended for long range connections like those on college campuses or television networks. Single-mode fiber optic cable can carry a 10 Gigabit ethernet signal up to 80 kilometers making it a popular choice among those who require a long range network that can handle a large amount of data at the SpeedaLite .