Maintain consistent 10 GbE connectivity where throughput and port density matter. The AddOn T520-CR-AO delivers dual open SFP+ ports on a PCIe 2.0 x8 interface, giving server teams a practical way to add fiber uplinks without changing the chassis design. Intel 82599 silicon provides a proven foundation for enterprise network attachment, while support for both single-mode and multi-mode fiber keeps deployment options open across short-reach and longer-reach links. This adapter fits servers that need dependable bandwidth for virtualization hosts, storage traffic, backup paths, or aggregation uplinks. The open SFP+ design lets you select optics that match the environment, which is useful when standardizing across mixed fiber runs. With a plug-in card form factor and lifetime warranty, it is positioned for infrastructure teams that want stable performance and long service life rather than a low-cost stopgap. For environments where a failed or under-specced NIC can slow the entire rack, this card offers a straightforward upgrade path with the right balance of compatibility, density, and durability.