Canon EOS-1 D X Mark II Instruction Manual page 435

Recording card, image size setting
When you press the <H> button to select the card or set the image
size, you can select to do it with the rear LCD panel or with the LCD
monitor.
Rear LCD panel
You can press the <H> button, then turn the <6> or <5> dial
while looking at the rear LCD panel.
LCD monitor
When you press the <H> button, the [Img type/size] or [Record
func+card/folder sel.] screen will appear. Pressing the button
toggles between the two screens.
OFF: Disable H button
You cannot select the card or set the image size by pressing the
<H> button. It can prevent the image size or recording card from
changing when the <H> button is pressed accidentally. Select
the card or set the image size from the menu screen.
3 Custom Function Settings
C.Fn5
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