All Bosch 18V batteries. e.g. this one Bosch Starter Set 18V (2.5 Ah+AL 1830 CV) (18 V, 2.50 Ah)

But you can buy them directly as a set: Bosch ALB 18 (battery-powered, leaf blower)

Bosch Akkupack PBA 18V Lithium-Ionen (18 V, 2.50 Ah)