Western Digital Se WD4000F9YZ 4TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Enterprise Internal Hard Drive. 4TB 3.5" SATA enterprise hard drive spinning at 7200 RPM with 64MB of cache on a SATA 6.0Gb/s interface. Built for 24/7 datacenter and server workloads. Every drive is professionally tested and inspected before shipment.