The AIRlock is awesome little gadget, when in place the tailgate will stay a tiny bit open to get air in.
The clue is, that when the tailgate can be locked as usual, so NO STRANGER can open the tailgate! Ideal addition to create extra, but safe air flow in your van.

.
Great solution in addition to rear tailgate a fly-screens. While the fly screens keep the insects out- the AIRlock will get the Airflow in.

Very safe, as no one can open the tailgate while the AIRlock is locked, a great piece in mind especially for single travellers, surfers and free campers.