Part of the Erbauer 18V EXT one battery system, running multiple tools for increased flexibility. Erbauers highest performing battery, with 21700 high performance cells for maximum power and endurance. Keep Cool battery technology actively manages temperature, so cells avoid overheating, giving more power, longer run time and increased battery life. Shock resistant design and a battery charge indicator. Compatible with all Erbauer EXT 18V cordless tools.