Canon EOS-1D X Mark III Advanced User's Manual page 25

(1) Lens mount index
(2) Depth-of-field preview button
(3) Multi-function button 2
(4) Self-timer lamp
(5) Shutter button
(6) Grip
(7) Vertical-grip On/Off switch
(8) < > Vertical-grip AF area selection/
Vertical-grip AF method selection/
Vertical-grip multi-function/
Vertical-grip FE lock/
Vertical-grip multi-spot metering button
(9) Vertical-grip main dial
(10) Vertical-grip shutter button
(11) Hand strap mount
(12) Mirror
(13) Movie shooting microphone
(14) Lens lock pin
(15) Lens release button
(16) Lens mount
(17) Contacts
(18) Vertical-grip depth-of-field preview button
(19) Vertical-grip Multi-function button 2
(20) Tripod socket
(21) Serial number
(22) Accessory positioning hole
(23) Body cap
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