Western Digital Surveillance 8TB Purple (WD84PURZ) WD WD84PURZ Purple Series, 8TB 3.5" Hard Drive, SATA 6GB, 128MB Cache, Supports up to 64 HD Cameras Device Type - Hard drive - internal Capacity - 8 TB Form Factor - 3.5" Interface - SATA 6Gb/s Buffer Size - 128 MB Advanced Format technology, surveillance system compatible, AllFrame 4K, tarnish-resistant Width - 4 in Depth - 5.8 in Height - 1 in Weight - 720gms Drive Transfer Rate - 600 MBps (external) Internal Data Rate - 194 MBps Spindle Speed - 5640 rpm