SMOK TFV8 X-Baby Q2, X4 and M2 coils are designed for the TFV8 X-Baby tank. Q2 is an innovative dual coil with 0.4ohm resistance and supports 40 – 80W power; X4 has a Quadruple Coil Design and supports 30 – 70W power; While M2 is unique dual coil with 0.25ohm resistance and can be compatible with 3.7V mechanical MOD such as Stick V8