The AC Power Supply unit operates the Z1/Z2 CPAP Machine and is the power source that supplies the device with wall outlet power.
The AC Power Supply will only work with the Z1/Z2 Travel Machine, and does not come with any other product or accessory.
I thought the Z1 was a battery operated device: why is there a power cord for it?
The Z1 can be operated by battery power, but is built to be operated with a power cord. The power cord will be useful on longer trips, where you won't want to worry about charging your battery.