Canon EOS R5 Mark II Advanced User's Manual page 56

2.
Insert the card.
The card in the rear card slot is [ ] (CFexpress card), and the one in
front of it is [
CFexpress card: With the card label facing you, insert the open side of
the card (2) into the card slot. Inserting cards the wrong way may
damage the camera.
The gray card-eject button pops out.
SD card: With the card label facing you, insert the card into the card
slot until it clicks into place.
3.
Close the cover.
Close the cover and slide it as shown until it clicks shut.
Card 1 (CFexpress card)
Card 2 (SD card)
] (SD card).
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