Even in the dark, you can type easily with the brightly backlit, concave keys that cradle the fingers, and provide precise illumination on the Logitech K800. Only the characters are illuminated, for beautiful, distraction-free typing. The keyboard automatically adjusts the backlighting to suit the lighting conditions or it can be adjusted manually with the press of a button. Sensors turn the backlight on and off automatically based on proximity of the user's hands. The PerfectStroke key system distributes typing force evenly across key surfaces, making every keystroke comfortable, fluid, and whisper-quiet. Simply plug in the universal micro-USB cable for three to six hours and you get up to 10 days of battery life, and can even type while it's recharging. The tiny 2.4 GHz wireless receiver stays in your laptop, providing long-range wireless connection that virtually eliminates delays, dropouts, and interference. Plus, you can easily add a compatible wireless mouse or keyboard without the hassle of multiple USB receivers.