Select 120 V Basic and Metered PDUs feature two separate input power circuits with corresponding, color-coded (black and gray) power cords, circuit breakers, outlets and (if applicable) current meters. The PDUs are designed to accommodate the two, redundant input power cords found on most mission-critical network devices. Using the PDU's two separate circuits, managers can build a fault-tolerant rack installation by sourcing power from two separate power sources. Depending on the desired level of power protection, the two sources can be two UPS systems, two generator-supported utility wall outlets or one UPS system and one generator-supported utility wall outlet. Since PDUs with dual input circuits consolidate the features of two models into one housing, it reduces clutter and allow for increased airflow in racks.