QSFP-40G-SR4, known as Quad Small Form-factor Pluggable 40 Gigabit Ethernet Short Reach 4, is a high-performance optical transceiver module designed for data communication applications. Simply put, its mission is to transmit data quickly over short distances. It operates at 850nm, transmits data over four parallel 10Gbps lanes, and typically supports distances up to 100m on OM3 and 150m on OM4 fiber. What does 40GBASE-SR4 mean? 40GBASE-SR4, also called QSFP-40G-SR4, provides short-range 40GbE connections. 3ba 40GBASE-SR4 specification, and the QSFP+ SR4 module uses an MTP/MPO ribbon fiber connector to deliver 100 meters on OM3 fiber and 150 meters on OM4 fiber. The modules most commonly used in 40G solutions include 40GBASE-LR4 QSFP+, 40GBASE-SR4 QSFP+, and 40G LR4 PSM.