WD Purple drives are engineered specifically for surveillance to help withstand the elevated heat fluctuations and equipment vibrations within NVR environments. An average desktop drive is built to run for only short intervals, not the harsh 24/7 always-on environment of a high-definition surveillance system. With WD Purple, you get reliable, surveillance-class storage that’s tested for compatibility in a wide range of security systems, and some of our latest models (WD22PURZ, WD42PURZ, and WD63PURZ) have improved power efficiency. Exclusive AllFrame™ technology helps reduce frame loss and improve overall video playback.