M12, Red Lithium XC 4.0 Extended Capacity Battery Pack, 12V, Redline Intelligence Provides Optimized Performance & Overload Protection Using Total Communication Between Tool, Battery & Charger, Offers Long Lasting Performance & Durability, Fuel Gauge Onboard Displays Remaining Runtime For Less Downtime On The Job, All-Weather Performance Delivers Fade Free Power In Extreme Jobsite Conditions, Powers Most Milwaukee M12 Cordless Power Tools.