Wd my book duo dual drive raid storage 16gb usb 30 external hard drive dual drive performance equipped with two wd red hdds my book duo gives you massive capacity with twice the speed by combining drive performance you get up transfer speeds up to 324mbs so you can transfer a full hd video or your entire media collection with ease read speeds mbs testing by wd resulted in actual transfer rates of 3249 mbs on 16 tb configuration performance may vary based on configur