Compatible with all Milwaukee M18 cordless tools, the M18 REDLITHIUM XC extended-capacity battery delivers 4 Ah (72 watt-hour) of run time even in sub-zero temperatures. Each 18V lithium-ion battery is laden with new-age REDLINK circuitry engineered to prevent overloads and protect against cell-damaging discharge. Revolutionary cell monitoring and temperature regulation prolong this battery's operation and life expectancy, meaning fewer work interruptions and more recharges than ever. Professionals depend on heavy-duty, long-lasting performance and Milwaukee delivers with this 18V battery pack.