SMOK TFV8 X-Baby X4 Replacement Coils are specifically designed for the TFV8 X-Baby tank. These coils feature a resistance of 0.13 ohms, making them suitable for wattage settings between 30 to 70 watts, with optimal performance achieved between 45 to 60 watts. They are not compatible with the Baby or Big Baby range, ensuring precise fit and function for the intended device.