The WD Red WD30EFRX 3TB Internal Hard Drive is designed to operate for home and small office NAS. As the only hard drive with 1-5 drive bays which is designed for NAS systems, the WD Red WD30EFRX 3TB Internal Hard Drive optimizes data management for enterprise-class environment. This 3.5" internal hard drive has undergone extensive tests to guarantee superior performance for demanding system requirements. The WD Red WD30EFRX 3TB Internal Hard Drive is built to offer the highest form of reliability.