M18 REDLITHIUM™ FORGE™ are Milwaukee's most powerful, fastest charging, and longest life batteries. The M18™ REDLITHIUM™ FORGE™ batteries are COOL-CYCLE™ capable. COOL-CYCLE™ Active Cooling System provides high-speed cooling for less downtime. Patented ingress coating provides increased protection to maximize active cooling through an upgraded venting design. The high-speed cooling feature works with M18™ chargers that have COOL-CYCLE™ capability. These lithium-ion batteries have the longest life, the most recharges, and the best performance over the life of the battery. They are also designed with resistant housing for increased protection against exposure to common oils, greases, and solvents. Built-in REDLINK™ Intelligence protects the battery from overloads, preventing you from damaging your cordless power tools in heavy-duty situations. The REDLITHIUM™ FORGE™ batteries are fully compatible with 250+ M18™ solutions.