The ECHO 58-Volt 4.0Ah Lithium-Ion Accessory Battery Pack features triple protection electronics to prevent overcharging, overheating and overloading. With a 1-hour recharge time, users can complete big jobs without worrying about running out of power. 4.0 Amp hour lithium-ion battery 1 hour recharge time Triple protection electronics prevent overcharging, overheating, and overloading Integrated fuel gauge Superior cold weather performance Compatible with all ECHO 58-Volt lithium-ion tools and chargers