For the Davides the converter ring should come with a small white grommet/plug looking thing that "plugs" into the air shaft or (since I can't find any right now) take the silicone piece that goes over the chimney of a standard coil, use nail clippers to cut the sides off, place the resulting silicone disc on top of the air shaft hole, then screw in tight the assembled base, ring and BVC. Believe this "plug" is suppose to prevent any leaks into the air shaft.
Found the rings at Vapor Kings for the ProTanks. Theirs come with the silicone piece I clipped above. The converter ring by itself does work with either the Davide or ProTanks.
Am using right now, a Davide with the made silicone disc above, airflow adjustor, ring and BVC atop an iStick. No leaks so far! Good luck
