Western Digital has announced the My Book World Edition II dual-drive storage system. One big advantage of this external hard drive is that the dual drives are shipped in a mirrored RAID 1 configuration for an extra level of protection. You can reconfigure it if you’d prefer twice the space instead. Otherwise, you can expect all the usual NAS-related features, a “cooler, quieter, eco-friendly design,” a USB port to add on an extra USB drive, and a nifty capacity gauge to let you see how much space is available at a glance. Unfortunately this 4TB storage system has a rather hefty price tag of $700; you can get a 2TB drive for around $400.