The Cisco GLC-LH-SM is a Small Form-Factor Pluggable (SFP) transceiver for 1 Gigabit Ethernet, supporting both Multimode (MMF) and Single-Mode Fiber (SMF) for up to 10km links, using a 1310nm wavelength, featuring a dual LC connector, and offering features like Digital Optical Monitoring (DOM) for reliability in enterprise/data center networks, ideal for long-distance connectivity over standard fiber.