Bosch BAT819. . Features: Bosch's smallest and lightest 2.0 Ah battery pack available maintains the same footprint as previous generation 1.3 Ah 36V batteries. Maximizes battery runtime on the jobsite and eliminates user frustration in looking for charged battery. Longer battery runtime increases productivity for critical system tools like rotary hammers, drill drivers and saws. Fuel gauge ensures that users always know the power level. CoolPack heat-conductive housing cools internal cell temperatures for longer life.