From the official release: "Microsoft Corp. today unleashed the SideWinder X8 Mouse, offering wireless freedom with wired performance with a 2.4GHz wireless connection that is built for lag-free play. The latest SideWinder mouse features an innovative play-and-charge system to ensure a nonstop gaming experience — up to 30 hours of active gaming on a single charge — with no need to stop the game to change batteries. The SideWinder X8 Mouse is a top performer thanks to Microsoft’s new, proprietary BlueTrack Technology that gives this mouse the best frame rate, speed and acceleration on the market and a tracking range from 250 to 4,000 dots per inch (dpi)..."