Open air style racks have open tops the top on all AP economy line racks are completely closed and under 1/2 inch shelf, no such thing as a AP open air rack. I think your confusing an open air rack with a open sided rack, the AP economy line are opeen sided racks. Also I have a RB CB-70 and a AP economy line rack (15qt/32qt combo) they hold humidity and temps exactly the same in my bedroom (room w/ frequent temp fluctuation), both are setup with belly heat. Considering you have a proportional thermostat there's literally no difference what so ever. If you want to compare these to open air racks such as Freedom Breeders or Visions then they are hundreds of dollars cheaper, but thats a completely different league of rack with a completely different purpose meant to be in a temp controlled enviorment.