Airflow to flasks (Burnout)

Hi Formlab users,

I’m new in 3d printing/casting.

Today have I received my burnout kiln. I have bought a Prometheus Kiln Pro-7 on cooksongold but unfortunately did cooksongold not have any flasks.

Therefore do I need to purchase flasks, there will fit the kiln.

And now to the question.

The chamber height on the kiln is 155mm, how heigh can I buy the flasks and still get a good burnout.

Best Regards

4 to 4.5 inch flask considering it can’t sit flush on the bottom of the kiln.