Kensington Pro Fit Mid-Size Wireless Mouse, Graphite Gray (K72423AM) Compact size for travel convenience, clutter-free wireless technology and storable Nano receiver Ergonomic right-handed design, has scroll wheel with middle button and pointer speed quick-select 2.4 GHz wireless for long range with minimal interference High-definition optical sensor (1750 DPI) for responsive control Extended battery life up to 12 months; Compatible with Windows 8