Which fiber optic standard utilizes a 50 micron core?

Multimode fiber can be either 50 microns or 62.5 microns at its core. The maximum distance for a 50-micron fiber is 550 meters utilizing the 1000Base-LX specification. Unshielded twisted pair (UTP) is used in copper Ethernet cabling of hosts and network equipment. Single-mode fiber-optic cable is around 7 microns thick and is used for long-distance communications. Shielded twisted pair (STP) is used in industrial settings when there is the potential for electrical magnetic interference (EMI).