DeWALT DCB609 Rechargeable Battery Pack, 20/60 V Battery, 9 Ah

The dual-voltage 20 V/60 V Max Flexvolt® 9 Ah battery automatically changes voltage when you change tools, providing up to 6X runtime in 20 V Max tools and the power of corded in 60 V Max and 120 V Max tools. Take on tough jobs with this battery because patented technology and large format cells mean it runs cooler than the leading competitor 9 Ah battery pack under a constant discharge. This is the battery for Flexvolt® power and long runtime.