Keep high-speed aggregation links stable across longer multimode runs with this 40G ESR4 QSFP+ module. It is designed for 40 GbE deployments that need 400 m reach and interoperable MPO connectivity, making it a practical fit for spine-to-leaf uplinks, campus backbones, and storage fabrics where link consistency matters. The ESR4 design supports 10G SR interoperability, which helps simplify mixed-environment migrations and reduces friction when aligning optics across existing infrastructure. That matters when you are extending capacity without reworking the entire fiber plant. For teams that value predictable performance over lowest-cost optics, this module offers the right balance of reach, compatibility, and deployment flexibility. It is a straightforward choice when the network design calls for multimode transport, short-to-midrange distance, and a transceiver that integrates cleanly into established Extreme Networks environments.