The USB Charger Cradle is the Optional charger for the Targus Wireless Optical Mini Mouse. It's the ideal solution that addresses high power consumption issues faced by all wireless optical mice. The majority of wireless optical mice require frequent Battery replacement (every 1 to 3 months depending on usage) leaving it up to you to ensure there are spare Batteries on hand. Includes rechargeable batteries Provides a Docking station for the Mini Mouse when it?s not in use; keeping the Desktop organized Connects to the laptop/desktop PC via a USB cord and provides a connection/shelter to the thumb-sized USB wireless Receiver via a built-in USB port Small, Lightweight Ergonomic Design When used on the desktop, it transmits RF signal to the USB receiver that fits in the charger cradle, and sends signal to the laptop/desktop PC When not in use, the Mini Mouse can dock in the charger cradle for recharging, ensuring the batteries are always fully charged .