The wireless battery-powered switches can be used in 2 modes: stand-alone and connected mode.
In stand-alone mode, they work autonomously without connection to a wireless bridge (550-00640) or wireless smart hub (552-00001).
In connected mode, they are connected to a wireless bridge (550-00640) or wireless smart hub (552-00001) and more functions are enabled.
Both modes are further discussed on:
Wireless battery-powered switch, onefold, Zigbee®
Wireless battery-powered switch, twofold, Zigbee®
Wireless battery-powered switch, fourfold, Zigbee®