Western Digital WDG1SU3200N My Book Premium ES 320 GB USB 2.0/eSATA External Hard Drive Form Factor - 3.5" x 1/3H Dimensions WxDxH - 2.23 x 5.63 x 6.78 inches Weight - 2.9 lbs Weight - 2.9 lbs Interface - USB 2.0 / eSATA