With the nylon-encapsulated O-ring in place, use a tube or rod to slide the Racking Adapter body into the neck of a carboy.
Guide the threaded portion of the Racking Adapter body into the hole in the side of the carboy.
Hold the Racking Adapter body in place with the rod or tube and install the three nylon slip washers, the pointer (if desired), and the locking O-ring in that order. Apply a little water to the threads and install the nut.
Finger tighten the nut, using enough force so the Racking Adapter makes a good seal and can be comfortably, but not easily, rotated by hand. A sticky pad (jar opener) can make tightening easier. Observe the position of the pointer with respect to the stem of the Racking Adapter. Assuming the pointer and stem are not aligned, loosen the nut and reposition the pointer, so it will line up with the stem when the nut is re-tightened. Re-tighten the nut. It may be necessary to repeat this last step a number of times in order to achieve adequate pressure on the seals and line up the pointer.
Slide out the tube or rod and double check that the Outlet assembly rotates smoothly, but with enough resistance to indicate a good seal. Adjust the tightness of the nut as required.