The statement that each device is an extender is misleading AFAIK. Read the document, it clearly says that sentence BUT also says that only the devices that plug into the wall are actual extenders due to power requirements. Hence, base and an extender unit or chime pro. Misleading to be sure. Z-wave also works at a lower freq, which means it gets thru walls easier but can be overall slower. Technically, it depends on the efficiency of the protocol riding on the carrier wave, but that discussion is for another time.