This is a wall mount for the Lego NASA Apollo Saturn V (21309).
The screw holes are the same distance apart for each bracket. This makes it easier to get it level.
Note: The First and Second stage mounts are identical, except for the label. The third stage is higher up the wall-mount to account for it being narrower.
The dimensions of the bracket are be compatible with standard Lego bricks (without the studs).