****No Longer Manufactured****
Best alternatives that we do stock are linked below:
Both of the above will require different coils than your 16D's, there is a link in the description of each of the above clearo;s to the correct coils.
We would highly recommend changing to a more modern system as found in our beginner starter kits HERE. The 16D is no longer being manufactured as it is quite old and more modern and better performing devices have been developed. The two Kanger alternatives we listed above are also very old and it would not surprise us to see them go the way of the Dodo as well.