The Uwell Valyrian II 2 Replacement Coils is made of FeCrAl and 100% organic cotton fiber and has a honeycomb mesh design (except for quadruple coils). The combination of this material ensures a large heating surface and a uniform heating effect. Produce huge vapor. There are four types of this series, UN2 0.32ohm Single Meshed Coil - provides the smoothest and largest airflow; UN2-2 0.14ohm Dual Meshed Coil - provides huge and thick vapor, UN2-3 0.16ohm Triple Meshed Coil - presents the full and original flavor, 0.15ohm Quadruple Coil - provides massive clouds and great flavor. Incorporated in these coils is Uwell’s patented Self-Cleaning technology, which takes any condensation formed at the bottom of the atomizer head and reabsorbs it into the coil. Each has the brand's Pro-FOCS Flavor Technology that recycles airflow for a bolder, richer taste.