The Milwaukee M12 REDLITHIUM-ION Battery Packs are fitted with sophisticated electronics (REDLINK Intelligence) and overload protection which prevents the user from damaging their cordless power tool investment in abusive situations. The battery packs have a temperature Management System which keeps them in ideal temperature range to provide maximum life. Individual Cell Monitoring ensures optimal charge and discharge for maximum life. They offer up to twice the run time, 20% more power and up to twice the recharges compared to other lithium-ion technologies and or with previous Milwaukee battery technology. M12B Features: Battery capacity: 1.5ah. Battery chemistry: li-ion. Voltage: 12 volt. M12B2 Features: Discharge Protection - Prevents cell damage from over-discharge Integrated weld frame Cell separator Impact and vibration protective rubber M12B4 Features: Impact and vibration protective rubber Discharge Protection - Prevents cell damage from over-discharge Integrated weld frame