The SFP-10G-BX-D-40-ST is a Cisco SFP-10G-BX-D-40 compatible downstream fiber SFP transceiver which pairs with StarTech.com\'s SFP-10G-BX-U-40-ST. They are designed, programmed and tested to work with 10GBase-BX compatible Cisco switches and routers. The SFP+ transceiver module supports a maximum distance of up to 40 km (24.8 mi) and delivers dependable 10 GbE connectivity over fiber cabling. This SFP+ fiber module is hot-swappable, making upgrades and replacements seamless by minimizing network disruptions. StarTech.com offers a wide variety of SFP modules and direct-attach SFP Cables, providing the convenience and reliability you need to ensure dependable network performance.