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.