The safety stop screw will prevent the lower camera platform assembly
from dropping out of the square rail while you tighten the two allen
(hex) head securing bolts (arrowed below) using only hand pressure, do
not over-tighten.
It is also possible to mount the lower camera to the left of the upper
camera using the left hand vertical holes. However this is not the
optimum design position and should only be used if you need left view
straight through and right view via the mirror.
STEP 5:
Add the accessory plate to the end of the top rods, secure the four gold
locking tabs.
