I4U NEWS reviews the Microsoft Bluetooth Notebook Mouse 5000.
A quote from the article:
Microsoft Bluetooth Notebook Mouse 5000 Review
Power for the Microsoft Bluetooth Notebook Mouse 5000 comes from a pair of included AAA batteries and the mouse features a battery life indicator that glows when it's time to replace the batteries. Microsoft says you can get three months of use out of one set of batteries.
Microsoft Bluetooth Notebook Mouse 5000 Review