The Milwaukee M12B6 Redlithium-ion battery electronics offers superior performance and delivers. This 6ah battery gives you improved runtime and power on the tool. The on board Fuel gauge allows the user to know the amount of power left in the battery.The discharge protection prevents cell damage from over discharge. The REDLINK digital overload protection prevents users from damaging their tool in abusive situations. It has a Temperature Management System which extends the life of the battery by keeping it in the ideal temperature range and can run in temperatures down to minus 20 degree celsius. This battery is compatible with every Milwaukee M12 tools allowing interchange with about 40+ M12 Items