Up until now Western Digital have separated their hard drive lines into three; Blue for consumer drives, Green for low-power drives and Black for performance. This has now been expanded with a fourth colour added to the stable; the WD Red NAS hard drive range. Western Digital tout these as being designed specifically for the usage patterns typically seen in a network-attached-storage (NAS) device – generally 24/7 operation, potentially poor ventilation and the likelihood of being in a RAID array of some description for mass media storage.