Are they vents or what?

What exactly is the purpose of the boxes under the dash on driver and passenger sides that have the latch that closes the door on the front. I've got one that broken on my Dart and would guess it is a floor vent, but can't find anything on eBay for that description. The rivets holding the door on my drivers side box are busted and I'm holding it together with duct tape. Can anyone help me find one??