- Directional Airflow refers to the process of turning a carbohydrate cap on a dab rig during combustion. Caps created for vertical airflow have curved holes which go far into the rig for better convection. The airflow carbohydrate cap is a very important part of the dab rig and the better the design, the better the ability to direct the airflow to corners of the quarts banger that normally would not be reached. This allows you to spread the material evenly across the heated surface. It basically makes sure that the concentrate is all being vaporized and there are no remains that are wasted afterwards.