ARB RD149 - Manual (Page 18)

3 Installing the Air Locker
16
NOTE : Be sure to insert the correct end of the center
compression nut into the bulkhead body. The thread
has been partially relieved on the bulkhead side of the
center compression nut to visually identify its
orientation. (Fig.10.)
Figure 10.
NOTE : Excessive tightening of the center compression nut is
not necessary to form a good seal around the tube
and may damage the O-ring, the seal housing tube, or
the threads of the compression nut.
NOTE : Make sure the seal housing tube is all of the way into
the center compression nut while you are tightening
it.