The Bosch CORE18V 4 Ah Advanced Power Battery is a compact battery delivering power in a lightweight solution. It allows you to get the power and lose the weight. The GBA18V40 delivers high power in a compact size for standard to medium-duty applications, such as drilling into concrete, metal and wood; metal grinding; cutting and even light-duty chipping. It delivers 2x the runtime and 60% more power compared to BAT612 18V 2 Ah battery. The GBA18V40 is designed with high-power lithium-ion cells, featuring a single layer of enhanced 21700 cells for greater battery efficiency. Cutting-edge battery design � includes copper end plates, power rails and a flexible circuit board for reduced resistance and increased efficiency. This Advanced Power Battery has Bosch-exclusive CoolPack 2.0 technology, which cools the battery faster and helps provide longer lifetime compared to Bosch 18V batteries without CoolPack 2.0. This compact battery weighs only 1.10 Lbs. but provides performance comparable to much heavier batteries in a lightweight solution. It is compatible with Bosch 18V tools and chargers and the AMPShare System. It also has a high-resolution charge-status indicator.