Basically, any 18V Bosch Professional battery fits. I use the one with art. No. 2 607 337 263 G2. The product designation is: GBA 18V 6.0Ah M-C. The newer ones have 6.3Ah and fit the same. I bought a set of 2 batteries of the above mentioned type and the charger. However, this is only worthwhile if you have other Bosch Professional tools. It may also be worth buying the more powerful GAS 18V-10L instead of the GAS 18V.