Features and Benefits:Onboard indicator light: Provides the status of the battery;Charge management: Charger communicates with the battery pack to ensure a full charge and battery protection;REDLINK™ Intelligence: Provides optimized performance and overload protection using total system communication between tool, battery and charger;All-weather performance: Delivers fade-free power in extreme jobsite conditions;Best-in-class construction: Offers long-lasting performance and durability;Versatility: Powers most Milwaukee M12™ cordless power tools;The M12™ REDLITHIUM™ XC4.0 battery delivers up to 2X more runtime, 20% more power and 2X more recharges than standard lithium-ion batteries. The M12™ REDLITHIUM™ 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 amp-hours of runtime. With Milwaukee durability built into each pack, this battery runs cooler and performs In addition to the battery pack, the starter kit includes the M12™ Battery Charger. The M12™ REDLITHIUM™ battery is fully compatible with all Milwaukee M12™ solutions.