Canon WFT-R10A Wireless File Transmitter for EOS R5 C & R5 Mirrorless Camera - Manual (Page 19)

Attaching Batteries
1.
Attach the batteries.
(1) Battery for the transmitter
(2) Battery for the camera
The camera and transmitter cannot be used together unless two
batteries are inserted.
(3) Battery holder
Press (3) until it clicks into place.
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