The Festool HighPower BP 18V 4Ah HPC-ASI Battery Pack 205034 Effortless work: At just 600 g, it is 20 Percent lighter and 50 Percent more compact than a 5.2 Ah battery pack. Full power: Thanks to the Li-HighPower cell technology, it is powerful enough for every application. Extremely durable: The high-current-resistant cells ensure durability. For stress-free work: The battery packs are, of course, completely covered with Festool Service. Dust extraction starts automatically: The Bluetooth version automatically starts the connected mobile dust extractor when the tool is switched on Bluetooth 1; Tensioner 18 V; Capacity 4 Ah; Weight 0.6 kg