The Bosch BAT838 CoolPack heat-conductive housing is specifically designed to cool internal cell temperatures for longer life. The Bosch BAT838 4.0 AH LITHIUM-ION battery delivers 50% more runtime versus a 2.6 AH battery without CoolPack technology. Bosch batteries are compatible with electronic monitoring systems (EMS) on Bosch power tools that regulates voltage for heavy-duty applications. The Bosch BAT838 battery is built with advanced technology high-capacity, low-resistance LITHIUM-ION cells. Features a fuel gauge to ensure that users always know their power level.