WD Red 5TB NAS Hard Disk Drive - 5400 RPM Class SATA 6 Gb/s 64MB Cache 3.5 Inch - WD50EFRX Specifically designed for use in NAS systems with up to 8 bays Tested for 24x7 reliability NASware firmware for compatibility 3-year limited warranty Small and home office NAS systems in a 24x7 enviornment