StarTech.com Dell EMC 3CSFP91 Compatible QSFP+ Module, 40GBASE-ER4, Single Mode (SMF) Fiber, 40GE Gigabit Ethernet QSFP+, LC 40 km, 1270nm to 1330nm, DDM, 40GbE QSFP+ Active Optical Cable - Lifetime Warranty (QSFP40GER4ES) - QSFP+ transceiver module (equivalent to: Dell EMC QSFP-40G-ER4) - 40GbE - 40GBase-ER4Q - LC single-mode - up to 40 km - 1311 nm