The Festool Energy Set SYS 18V 4x TBX 4/TCL 6 DUO bundles four 18V TBX 4 tabless battery packs with a TCL 6 DUO dual charger in a Systainer, built for Festool's 18V cordless platform. Tabless cell construction delivers strong output in a lightweight pack, and the TCL 6 DUO charges two batteries at once to keep tools in rotation with less downtime. Bluetooth-equipped batteries can automatically start a paired Festool CLEANTEC dust extractor when a cordless tool switches on, with charge level, temperature, and cycle data viewable in the Festool app. The set is compatible with most Festool 18V devices, with exceptions for the ETSC 125, RTSC 400, and DTSC 400.