M12, 12V, Red Lithium 2.0 Compact Battery Pack, Features Superior Pack Construction, Electronics & Performance To Deliver More Work Per Charge & More Work Over Pack Life, Offers 2.0A Hours Of Runtime, Battery Runs Cooler & Performs In Climates Below Zero Degrees, Compact Design Fits In Tight Work Spaces & Reduces User Fatigue, Powers Most Milwaukee M12 Cordless Power Tools.