The pic @211ratsbud posted shows IQSub T-pieces, which is a change from what mine has. It might be worth an email to Charlie if you're going to buy something new (or he might still have some non-IQSub around).
The ADV was an iqsub one. There was no baffle on it. It went on the exhale side.
No baffle meant that it would be easier for water to bypass the t-piece and go into the scrubber in the event of a flood upstream of the t-piece. Not ideal.
The ADV was optional at one point. I am not sure they can be ordered today. I had one for about 6 months then took it off and gave it to a friend of mine.