Attributes . 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) . Names