Airflow design dictates the amount of airflow running through the tank/pod.
Mouth-to-lung (MTL) coils are designed for tight airflow, low power output and higher nicotine strengths. MTL closely recreates the experience of a cigarette. If your Innokin device features variable airflow, try the tighter draw settings at first and then adjust the airflow to find your preferred draw.
Direct-to-lung (DTL) coils are designed for open airflow, higher power and lower nicotine strengths. DTL vaping produces a large volume of vapour and intense flavour. If your Innokin device features variable airflow, try a more open draw for the best DTL experience.
Restricted-Direct-Lung (RDL) coils produce more vapour than MTL coils and use less power and e-liquid than DTL. RDL coils are a good choice if you are looking for more vapour and flavour than MTL and less nicotine in each puff.