The Logisys CLK4 4" Cold Cathode Light Kit (Green) with Dual light tube has a dual inverter and PCI mounted On/Off switch. Define your case by adding a cold cathode florescent light (CCFL) kit to your case. Cold cathodes emit a neon looking glow, but they do so producing very little heat for the amount of light they give off, making them a standard choice by enthusiasts for lighting up computer cases. A cold cathode florescent light kit will add flare to any case.