Ergonomic Wireless Design: The J-Tech Digital V638s comfortable, ergonomic handshake design greatly reduces arm/wrist/hand strain while providing relief for carpal tunnel syndrome. Back/forward thumb buttons provide extra convenience. (Button functionality can also be changed or reassigned using third-party software.) Works on most non-metallic surfaces. The built-in lithium battery is fully rechargeable. Removable Palm Rest: This ergonomic mouse features a detachable non-skid anti-sweat palm rest that reduces drag, making it easier to maneuver the mouse across the surface of a mousepad, tabletop, desktop, etc. 4 Adjustable DPI Settings: Users can adjust responsiveness to 800, 1200, 1600 or 3200 DPI depending on their need and/or preference. 360-degree signal allows for full freedom of ergonomic mouse movement. Optical Tracking Technology ensures greater sensitivity for precise tracking on a wide range of surfaces. Wide Compatibility & 3 Power Saving Modes: Compatible with Wi