PiPO M9 pro OTA - Manual (Page 29)

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Select the book you want to share with another PIPO Device, and tap share
icon to invite other PIPO tablets. Make sure that all Incstage Reader
apps in different PIPO Device are opened at the same time, and you connect all
Device to the same WIFI.
Then the images on your PIPO Device you control will be displayed to other
PIPO tablets invited. Check the bellowing synchronization displaying.