A battery built for longer days. The DCB549 XR Flexvolt® 15Ah battery provides the highest capacity of any battery on The DEWALT® cordless system. It changes voltage when going from 54V XR Flexvolt® to 18V XR® tools and is compatible with almost all of your 18V XR® tools and chargers. In XR Flexvolt® tools it will deliver class leading 54V cordless power and in 18V XR® tools it will provide unparalleled runtime.