The GBA 18V 4.0 Ah battery is designed for extended runtime. Due to its higher battery capacity, it delivers 100% more runtime than the 18V 2.0 Ah model. This battery provides corded power with cordless convenience, maximum performance and sustained runtime. It is backwards compatible to 2008, allowing you to use it with new and existing Bosch Professional tools in the same voltage class. Bosch 18V ProCORE Battery 4.0Ah.