The DCB606 FLEXVOLT 20V/60V MAX* 6.0Ah** (** With DCB606 FLEXVOLT battery when used with DEWALT 20V MAX* tools compared to DCB201 1.5 Ah battery pack.) Battery pack changes voltage when you change tools, powering a line of powerful 60V MAX* tools, 120V MAX* tools, and backwards compatible to existing 20V MAX* tools and chargers. The battery pack is smart enough to know when to provide runtime for 20V MAX* tools (6.0Ah) and power in 60V MAX* and 120V MAX* tools