The insertion loss and link loss tests are paired with the Greenlee 567XL optical power meter, and the 573XL is an ideal 650nm LED light source for testing multimode fiber and connector insertion loss The 573XL can also be used in conjunction with an optical power meter to measure the link loss of installed optical cables. Equipped with optimal emission conditions for 200/230um step type multimode fibers, the 573XL LED light source is particularly suitable for testing and maintenance of local area networks (LANs), building networks, fiber distribution data interfaces (FDDI), and certain communication systems. In addition, multiple plug-in SOC adapters are suitable for industrial standard fiber optic connectors, making the 573XL an indispensable tool for LAN service engineers and other optical transmission system testing.