All paraffin heaters distributed in Europe must at least have the CE seal of approval. Certain countries such as France and Germany have additional safety regulations as well as the CE seal. These are assured via the NF and Tuv/GS seals of approval. For example NF/GS approved heaters are fitted with an infrared CO2 sensor to monitor air quality, and the fuel type is specified exactly. In combination with the correct fuel and instructions for use, these seals of approval (depicted below) have led to flue less paraffin heaters being regarded these days as a safe, flexible and frequently economical form of heating.