The M12 REDLITHIUM XC 4.0 Extended Capacity Battery Pack features superior pack construction, electronics and performance to deliver more work per charge and more work over pack life than any battery on the market. It offers 4.0 Ah of runtime. With Milwaukee durability built into each pack, this battery runs cooler and performs in climates below 0F/-18C. Managed by Milwaukee's exclusive REDLINK Intelligence, the battery features overload protection to prevent you from damaging your cordless power tools in heavy-duty situations, while the discharge protection prevents cell damage. The temperature management system and individual cell monitoring help maximize battery life.