avalung

been reading through some past threads and have a couple of questions...I have had only one near miss in my life, where a slide was triggered 8 hours after i skied it, and being my 4th trip to valdez, I seem to be avalanche crazy lately. I know bad karma, but I can't help it.
With the avalung II, do you have to wear this externally, or can it be worn inside next to my beacon?...I read the thread on the new backpack, and was wondering if anyone has any feedback there.

You need to wear it externally as it needs to be in contact with the snow in order to work....

It works by drawing air in from one location and expelling air out in a different location, hopefully minimizing CO2 buildup in what you actually breath.
So you don't want it in your jacket.