M18 REDLITHIUM XC 5.0Ah Extended Capacity Battery Pack, 18V, Superior Pack Construction, Electronics, and Performance, Delivers More Work Per Charge and More Work Over Pack Life, REDLINK Intelligence for Overload Protection, Discharge Protection Prevents Cell Damage, Integrated Temperature Management System, Individual Cell Monitoring, Operates in Climates Below 0 Degrees F with Fade-Free Power, Compatible with All M18 Cordless Tools.