VEHICLE SEATBACK

A vehicle seatback includes a mounting guide protruding rearward from the seatback and/or stowed inside the seatback (e.g., by rotation) and a guide locking device for locking and/or unlocking the mounting guide (e.g., into or out from a stowed state inside the seatback). Vertical height, relative to the seatback, of a convenience device installed in the seatback may be adjusted and/or fixed in the mounting guide.