DEWALT's DCB609 20 DEWALT 20V/60V MAX Flexvolt 9.0Ah Battery, Dual-voltage for ultimate flexibility 180 watt hours of energy in each battery pack Get 360 watt hours when using (2) Flexvolt 9.0Ah batteries in 120V MAX tools Get 6 times runtime when used in 20V MAX tools Runs cooler than leading competitor 9.0Ah battery for better efficiency. Two-Pack