The D-Link DEM-311GT is an SFP (Small Form-Factor Pluggable) transceiver designed for 1000Base-SX Gigabit Ethernet connections over multi-mode fiber. It features an LC Duplex connector and supports data transmission up to 550 meters at an 850 nm wavelength. The module is hot-swappable, energy-efficient, and compliant with IEEE 802.3z standards, ensuring compatibility with various networking devices and environments.