WD 640GB External Hard Disk Drive 3.0 - Black color

Energy Efficient, High Capacity StorageEngineered specifically for low-power applications, the External HDD drive kit has a 5400RPM spindle speed and a 8MB cache to provide energy-efficient performance at whisper-quiet acoustic levels. With reduced power consumption and heat generation, this drive will reduce power costs up to 50% over the life of the system compared to standard drives. It is optimized for standard laptops and small form factor PCs.
WD Blue Momentus Laptop Hard Drive9.5mm form factor for compatibilitywith multiple systems.Durable Mobility Anywhere, AnytimeLaptop HDD offers a feature-rich 2.5-inch drive for laptop upgrades and external enclosures. The Laptop HDD drive family offers innovative options, capacities up to 640gb with significant feature options. The WD Blue Laptop HDD drive is perfect for any standard laptop and meets your specific upgrade needs, whether it's more capacity or lower power consumption.