The WD Purple 3TB Internal Hard Drive is a surveillance hard disk drive with a 5400 RPM rotation speed and a 64 MB cache. It is compatible with PC and NVR systems and has a SATA III interface. The drive is designed for continuous surveillance systems and has security features. It comes with a 3-year manufacturer warranty and is part of the WD Purple product line. The drive has a 3.5" form factor and measures 5.79" in length, 4" in width, and 1.03" in height.
eBay