Vaporesso GT Coils are for NRG Tank and NRG SE tank. These coils creates bigger clouds than standard coils. NRG tanks are used in Revenger kits also. GT Cores are specially designed to fit into the NRG tank series. It comes in traditional cotton and Vaporesso significant CCELL Ceramic in different resistances, From GT 2 to GT 8, total 5 coil selection to choose from. Gear Up with GT Cores as you desire.