This compact fluorescent lamp has a special coating that produces a deep purple light and large amounts of ultra violet light. The invisible light is reflected back in the visible spectrum by fluorescent materials and dyes. White clothes glow brightly in the dark, fluorescent paints light up brilliantly. Ideal for special effect lighting in night Clubs, theatres and Anti-Drug use areas. (Not suitable for dimmer switches) Standard ES-E27mm screw cap.