The WD Red Pro NAS Hard Drive has a 16 TB digital storage capacity. This internal hard drive features a 3.5-inch form factor and operates at 7200 RPM. It uses a Serial ATA-600 interface with SATA 6 Gb/s connectivity. The drive includes a 512 MB cache and is designed for Network Attached Storage (NAS) and RAID environments. It is rated for workloads up to 550TB/yr.