The QF Replacement coils by Vaporesso are compatible with the SKRR S Tank and is designed to allow for bigger vape clouds and a richer flavour. With a combination of flax and cotton fibers to create a long lifespan and consistent flavour. The QF Coil By Vaporesso have a secondary airflow system to allow for bigger cloud creation and eliminating cold air intake gives warmer, richer flavours. Utilising different ratios of flax and cotton fibers to create the most consistent flavourful vape while maintaining a long coil lifespan. Combining the use of airflow and an internal reservoir, Vaporesso have minimized leakage to maximize the efficiency of your e-juice. The QF coils have a bullet-shaped inner structure controls airflow to prevent liquid from coming up through the drip tip.