G-Technology G-DRIVE G1 USB 3.0 4TB External Hard Drive, 7200RPM, 165MB/s Data Transfer Rate, Silver PA Interface: 1x USB 3.0 (compatible with USB 2.0) Data Transfer Rate: 165 MB/s Disk: 3.5" 7200 RPM drive System Requirements: Mac OS X 10.7 +Windows 8.1, 8 and 7 Dimensions (L x W x H): 7.7 x 5 x 1.26" / 19.55 x 12.7 x 3.20cm