Einhell Power X Change 18v Lithium Ion 4.0ah Battery - Twin Pack Power X-Change is the rechargeable battery system from Einhell. It is designed for multi functionality. With this advanced technology, you can use 18V rechargeable batteries with different capacity ratings to power any of the Einhell Power X Change range. 7-in-1 ABS: Active Battery Management System from Einhell. No memory effect - the battery can be recharged at any time, even if it is only partially discharged. No self discharging - always ready for immediate action even after being in storage for months. Compact and light - significantly lighter than NiCd batteries allowing better handling. Sophisticated charging technology - short charging time, optimum performance and maximum battery life. Consistently high performance - delivers almost the same power at the end of the battery life as freshly charged ones. 3 x running time - compared to the conventional NiCd batteries. 3-step LED battery control. Modern technology: Microprocessor controls permanently parameters. Rubber-coated housing makes sure high impact protection and grip.