ISub, iSub S, iSub G, iSub S, Isub V and iSub Apex Tanks. iSub KAL BVC Coils are compatible with all of the iSub tanks. 5 x Innokin iSub KAL BVC Coils 1.2 ohm (individually sealed). These bottom vertical coils (BVC) use Kanthal wire which have been developed by Innokin to significantly enhance airflow, vapour and flavour for great cloud production.