@Dramma Lamma : do you feel like your extra airflow (air that flows when the bottom inlet is blocked) is contributing to the “too wide-open” airflow and “too weak/diffuse” heat that other users are describing? I did the test @Dramma Lamma described, covering the bottom inlet, and isolated the air as coming through the holes between the battery and electronic compartments, where the battery spring terminals are screwed into the bodies. There are 2 separate 1/4” wide gaps, maybe 1/8” tall, that I could get to whistle by pulling through an empty stem, with the bottom air inlet blocked. So I carved up two little shreds of a wine cork, fit them into the holes above the battery terminals, and my Zion is much happier now. I’d advise anyone having concerns/troubles with too much airflow, not enough heat, try some cork or tape over those holes on the top of the battery compartment, see if that does anything for you. it’s easily reversible, impermanent, and seemed to make a difference.