Finally got my Zen II Brevis in and comparing it to my Z-Atty-U. Wick hole sizes are vastly different. I noticed the Zen II doesn't have an insulator in the wick hole like the Z-Atty-U does. That alone may be making up the difference. Does the ZAU need that insulator? I've been trying to make a wick small enough for the ZAU. What a PITA.