Guaranteed Authentic CCell TH2 Oil Cartridge uses a unique and state of the art ceramic atomizer as opposed to a cotton wick. The preferred battery for use with this cartridge is the CCell M3 or CCell Silo. These cartridges are designed for use with thick aromatherapy oils, and are not suitable for use with nicotine or tobacco products due to the wide aperture in the atomizer. Hole size corresponds to the viscosity of your aromatherapy oil. The higher the viscosity, the wider the required hole. We recommend 2.0 for thick oils.