The DEWALT XR POWERSTACK Slide Battery features stacked pouch cell battery technology providing a low impedance construction, the rate of flow of electrons is much higher thanks to the innovative internal pouch battery connectors, and electrodes. The XR Slide Battery provides a greater surface area versus a traditional cylindrical battery cell type, and it also benefits from superior thermal performance, versus cylindrical batteries. This increases battery durability, and improves the cycle life and results. The XR works with the complete line of 18V XR tools and chargers, bringing a new lease of life and power to existing power tools. This DEWALT DCBP518H2 POWERSTACK Slide Battery Twin Pack contains 2 x 18V DCBP518H2 POWERSTACK Slide Batteries 5.0Ah Li-ion.