The SMOK TFV4 TF-RCA is one of the most advanced rebuildable coil heads, made of patented Clapton heating wire. The SMOK TF-RCA coils provide easy wicking. The TFV4 Clapton coils add more surface area and improve the wicking exposure. SMOK has included two build screws on each side: a plus terminal and minus terminal. You can take advantage of the various custom builds and fine tune the coil head to your likely.