The DEWALT DCB606 FLEXVOLT Battery pack changes voltage when you change tools. It powers a new line of 60-Volt Max Brushless tools and 120-Volt Max Brushless tools. These versatile Lithium Ion battery packs are also backwards compatible with 20-Volt Max tools and chargers. Not only can you power more tools with DEWALT FLEXVOLT batteries, the longer runtimes mean you don't have to keep climbing down the ladder to change the battery pack.