Air moving through the chamber path, this is much more noticeable with the new WPA. When you insert it into your glass piece there's a little poof of vapour. From my testing, I'm seeing zero conduction happening. The effects definitely provide the purest convection feeling i've come across as well. The material doesn't burn off if you let it sit in the chamber and turn it on. If anything there could be a minute amount of heat conduction passing through the material itself once it gets clumped up towards the front end near the end of the bowl when rippin er hard but who knows. I'll accept the 100% convection claims.