Dimensions Length: 4.36" / 110.8mm Width: 2.70" / 68.5mm BlueTrack Technology BlueTrack technology works on virtually any surface in your home or office. Bluetooth connectivity Wireless Bluetooth technology allows instant connectivity and frees up a USB port. Hard Drive space 150 MB Hard Drive Other information 2 AA alkaline batteries required (included). You must accept License Terms for software download. BlueTrack Technology® does not work on clear glass or mirrored surfaces. Android System 2.3 and above (3.0, 3.1, 4.0, etc.). ©2015 Microsoft Android is a trademark of Google Inc.