Dewalt DCB547 and DCB546 FLEXVOLT Battery XR technology fully convertible 18/54v DeWALT Battery backwards compatible with existing 18v DEWALT products, yet with the option to amplify voltage to an unprecedented 54v X 9Ah / 6Ah great for use on larger more powerful construction power tools. Compared with 240v and 110v power tools even the most efficient cordless system provided a compromise between increased portability and reduced power, between greater ease-of-use and reduced run-time. DEWALT have recognised the frustrations these limitations cause the trade and engineered the DEWALT XR FLEXVOLT system to eliminate any and all restrictions, providing a 54v/18v cordless system that offers zero compromises. DEWALT XR FLEXVOLT Batteries have the dual advantage of unbeatable run-time .