This is a black bulk 1000 foot spool of indoor/outdoor rated Plenum fiber optic distribution cable intended for large installations of short range runs at 10 Gigabit speeds. It is composed of 2 multimode fibers (50 micron core) inside a water blocking Aramid yarn wrapped in a black PVC outer jacket. Multimode fiber is optimized to work with fiber optic equipment using light wave lengths of 850nm (nanometers) or 1300nm. The cladding diameter is 125 microns. The Graded-Step core and cladding of our black bulk 50/125 indoor/outdoor fiber optic cable is constructed using a high quality multimode fiber that is compliant with TIA/EIA 455-220A and IEC 60793-1-49. It also maintains compliance with legacy and LED based systems per TIA/EIA 455-204 and IEC 607-1-41. This particular cable is Plenum Rated. Plenum spaces are the area between floors or above office areas for heating/cooling airflow. If an office were to catch fire, this plenum area could easily allow the spread of the fire to more floors or across the entire building. Plenum rated cables are jacketed with a fire-retardant plastic jacket of either a low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer (FEP) for less toxicity during a fire.