The Cisco GLC-LH-SMD is an SFP optical transceiver module designed for 1000BASE-LX/LH Gigabit Ethernet over single-mode fiber, with optional support for multimode fiber via mode conditioning. It operates at a 1310nm wavelength, supports transmission distances up to 10 kilometers on SMF and 550 meters on MMF, and uses a Duplex LC connector. This hot-swappable module features FP laser transmitters, PIN photodiode receivers, supports Digital Optical Monitoring (DOM), and complies with IEEE 802.3z, SFP MSA, SFF-8472, RoHS, and CE standards.