The Bosch CORE18V 4.0 Ah Compact Battery is the next-gen Lithium-ion battery you owe it to yourself and your tools to buy. The single-layer battery features advancements in design to reduce resistance and increase efficiency, to improve the performance-to-weight ratio of tools used on the jobsite all day. Engineered with 21700 cell technology, the battery matches the power from the original two-layer 4.0 Ah battery with improved performance per cell. Bosch engineered its exclusive CoolPack 2.0 technology to manage the heat of the higher power-density cells, and it provides better cooling than the previous-generation CoolPack system. CoolPack 2.0 cools the compact battery 15% faster than previous 4.0 Ah double-layer versions. Compact 18V Li-ion battery is engineered to provide next-gen power and runtime, while losing the weight, for optimized performance High-power cells use enhanced 21700 cell technology, combined with advanced battery design for greater efficiency Cutting-edge cell design means this compact battery is engineered to improve performance in tools used on jobsite all day, plus CoolPack 2.0 heat management Bosch-exclusive CoolPack 2.0 technology cools the battery 15% faster than previous 4.0 Ah double-layer versions Lightest high-power battery weighs only 1.15 lb, but provides performance comparable to much heavier batteries Features a high-resolution charge-status indicator for your convenience