Lenovo 540, Ambidextrous, Optical, RF Wireless, 2400 DPI, Sand Lenovo 540. Form factor: Ambidextrous. Movement detection technology: Optical, Device interface: RF Wireless, Movement resolution: 2400 DPI, Buttons type: Pressed buttons, Buttons quantity: 4, Scroll type: Wheel. Laser color: Red. Power source: Batteries. Product color: Sand