The 40G-QSFP-LR4-ST is a Brocade 40G-QSFP-LR4 compatible fiber transceiver module that has been designed, programmed and tested to work with Brocade brand switches and routers. It delivers dependable 40 GbE connectivity over fiber cable, for 40GBase-LR4 compliant networks, with a maximum distance of up to 10 km (6.2 mi).