I have found the conduction screens to be the only ones that really work for dry herb. The dry herb cans with lids burn the material right up with no vapor. The convection screens also burn material faster and have very little vapor. The conduction screens due to their open sides have to be filled in the chamber and the area is extremely small and hard to not make a mess. They would not work for travel for extras pre filled, so you are very limited to just the two chambers filled for travel, unless you are somewhere with a table to work on and very discreet.