LG Digital Signage Owner's Manual page 22

22
How to Join Sets
1
Join other sets using screws for fixing the VESA wall mount in the same way as above.
2
After joining the sets, use the tiling guide to adjust the gap between the sets.
39 mm
3
Now the 2 x 2 tiling is complete. You can tile in various combinations, such as 3 x 3.
Set 4 joined to the rest of the sets (2 x 2 tiling)
(M4 x L8)
54 mm