Voltage: 20VAmperage: 4.0AhBattery Chemistry: Lithium-IonPremium XR Lithium-Ion Pack Provides Up To 33% More Capacity Than Standard 20V Max Battery PacksNo Memory And Virtually No Self-Discharge For Maximum Productivity And Less Downtime3-LED Fuel Gauge System Allows Immediate Feedback On State Of ChargeWeighs Only 1.42 lbs. Allowing User Less Fatigue Over Longer Periods