Compact fluorescent lamps are low pressure discharge lamps that operate on the following principle: After ignition radiation from the mercury vapor in the glass tube is converted by the phosphors inside the glass tube into visible light, in a light color that depends on the phosphors used. Gear control ensures the correct luminous flux is emitted. In integrated compact housing fluorescent lamps and circular lamps the control gear is integrated into the lamp, while external control gear is required for non-integrated CFLs