The M18™ REDLITHIUM™ XC4.0 System Starter Kit includes an M18™ REDLITHIUM™ XC4.0 battery pack as well as an M18™ and M12™ Multi-Voltage Charger to pair with any M18™ tool-only option to make your own tool kit. With Milwaukee durability built into each pack, the REDLITHIUM™ XC4.0 battery pack runs cooler and performs in climates below 0F/-18C. Managed by Milwaukee’s exclusive Red link Intelligence, the battery features overload protection to prevent you from damaging your cordless power tools in heavy-duty situations, while the discharge protection prevents cell damage. The M18™ & M12™ Multi Voltage Charger recharges batteries sequentially, reducing your time to manage charge cycles. The charger communicates directly with the battery pack to monitor cell voltage, temperature and charge status to ensure a full charge.