Cold Cathode Fluorescent lamp (CCFL) is an element used within some Nixie tubes, gas discharge lamps, and gas filled tubes and vacuum tube. 

Cold Cathodes do not employ a cathode heater because it is not a deliberately heater; such a cathode is referred to as cold cathode.  The CCFL light bulbs are similar to the compact Fluorescent light versions but 100% Dimmable. They screw into standard lamp sockets. The Lifetime is ranging from 24,000Hr – 26,000Hr and the wattages ranging are 3w-10w. 

The CCFL light bulbs come in many shapes and sizes. When purchasing CCFL, consult the seller for recommendations and consider the following: the Coating (Clear, frost, white, LV, yellow, blue, green and red) and colors (Kelvin), the shape and the match lumens to the incandescent light bulb being replaced.