Western Digital - WD 8TB Purple Surveillance Internal Hard Drive - 7200 RPM Class, SATA 6 Gb/s, 256MB Cache, 3.5" - The WD Purple surveillance storage is built to handle up to 64 cameras per drive and is designed for 24/7, always on, high-definition surveillance security systems with more than eight bays. - With a wide range of industry-leading enclosures and chipsets supported, you’re sure to find the configuration and compatibility that’s right for your NVR. - low power consumption is a must in a high-temperature, always-on surveillance environment. Intelliseek technology helps reduce damaging ambient noise and vibrations.