The DEWALT XR FlexVolt Slide Li-ion Battery stands at the forefront of cordless technology. The worlds first convertible 18/54V battery, offering unprecedented levels of power. Provides the unique ability to power heavy-duty construction power tools whilst still being compatible with existing DEWALT XR 18V products and offering increased run time. It offers users increased run time, over any of the 18V XR 4.0Ah or 5.0Ah Li-ion batteries.