E-Liquid Capacity: Ranges from 2.0ml (TPD) to 20ml or more. Coil Resistance: Typically around 1.0Ω or 0.6Ω (for dual mesh coils). Nicotine Salt: Available in various strengths, commonly 20mg or 50mg. Materials: Food Grade PC + Silicone (and often Stainless Steel for the casing). Charging Port: Type-C.