Send 100 Gigabit Ethernet over a single single-mode fiber strand where duplex-fiber capacity is unavailable or needs to be conserved. The ACCORTEC QSFP-100G-LR20BD-U-ACC is a 100GBASE-BXU QSFP optical transceiver with a simplex LC connector and a maximum supported distance of 20 km. Its BXU optical direction supports a bidirectional optical link using complementary directions at the two ends. Install the module in an Arista-compatible 100 GbE QSFP interface when the link design calls for single-fiber bidirectional transport rather than a conventional duplex optical path. The simplex LC presentation makes the physical fiber connection distinct from duplex-LC optics: one fiber strand carries the link, while the far-end optic must provide the complementary BX direction. Single-mode fiber supports the stated long-reach connection. For network architects, the important selection points are 100GBASE-BXU operation, the 20 km reach category, simplex LC connectivity, and Arista compatibility. These characteristics distinguish it from short-reach, duplex-fiber, or non-bidirectional 100 GbE optics. Match the installed interface, fiber path, and required BX direction before deploying the link. This module provides a 100 Gbps optical Ethernet connection for fiber-constrained long-distance paths.