400G QSFP-DD DAC (Passive Direct Attach Copper) enables high-bandwidth 400G links and supports 400G Ethernet rate. It is high-speed, cost-effective alternatives to fiber optics in 400G Ethernet applications. The 400G QSFP-DD DAC cable contains 16 high-speed copper pairs, each operating at data rates of up to 53Gb/s, which are suitable for very short links and offer a cost-effective and power-efficient way to establish a 400-Gigabit link between QSFP-400G ports of switches/routers within racks and across adjacent racks.They enable higher port bandwidth, density and configurability at a low cost and reduced power requirement in the data centers. AscentOptics provide high performance QSFP-DD-to-QSFP-DD copper direct-attach cables in lengths of 1, 2, 2.5, and 3 meters.