ARB RD121 - Manual (Page 18)

3 Installing the Air Locker
16
Figure 7.
Figure 8.
NOTE : To best determine the correct vertical position of the
drilled hole, measure down from the machined face
(shown at the top of the picture in Figure 8.) a
distance of 13.5mm [17/32”] and mark the horizontal
line which the hole is centered on. Then refer to
Figure 9. for the correct position on that line to start
drilling.