When the link needs more reach than a short-reach SFP can provide, this 1000BASE-BXD module gives you a clean path to 1 GbE over single-mode fiber. With a 20 km reach, it fits campus backbones, building-to-building runs, and metro edge connections where dependable distance matters more than density. The bidirectional optical design uses 1490 nm and 1310 nm wavelengths to send and receive traffic over a single fiber strand. That reduces fiber consumption and keeps the design practical in environments where spare strands are limited or where the plant is already heavily allocated. Arista compatibility makes this module a straightforward option for teams standardizing on supported third-party optics. It is the kind of part that earns its place by fitting cleanly into existing infrastructure without forcing a redesign. Choose this model when you need a compact, hot-swappable SFP for medium-distance single-mode links and want to avoid overbuying reach you will never use. It delivers the right balance of distance, fiber efficiency, and platform fit for disciplined network builds.