Electronic ballasts are mainly used to start fluorescent and discharge tubes. Non-LED technology tubes require a ballast to provide sufficient starting voltage and to adapt the current required by the tube. They guarantee a constant level of illumination, regardless of the voltage fluctuations of the mains. The PHILIPS 218 HF-S TL-D II Selectalume double Tube Electronic Ballast is intended for use with indoor luminaires such as spotlights, direct lighting (downlights) and recessed luminaires, which are commonly used in offices, shops, industries, hotels, restaurants and other applications where control devices are used and on/off switching is occasional. For installations with watertight screens and strips that include a ballast, the space occupied by this device must be considered. It can be installed on the surface or in a false ceiling.