GIGALIGHT 200G QSFP-DD ER4 optical transceiver module is used for long-distance transmission in the field of data communication or telecommunications, and is in line with the 200G Ethernet transmission protocol. The product can convert 8 channels of 25Gbps (NRZ) electrical input data to 4 channels of 50Gbps (PAM4) optical signal, and also can convert 4 channels of 50Gbps (PAM4) optical signal to 8 channels of 25Gbps (NRZ)electrical output data.This series transmits over a pair of single‑mode fibers with a maximum reach of 40 km.