TF-T2 Standard Core and Air Core Coil Heads are dual coils with a high resistance and lower power.  They also have  two types features available, standard core and aire core. Inside the Standard Core, all airflow will go through the heating coils, and become warm vapor.  The Air Core with more air holes, in which some airflow will not go through the heating coils, thus producing half cold and half warm vapor for better flavor. There are also other 4 kinds of type coil head coming soon.