Coolers and cases usually have their own fans, but for those with very specific tastes, there are options to change things a bit.
Fans with colored LEDs are one of the easiest ways to add color and shine to a computer.
Whether they are installed on CPU or GPU coolers, or just added to a case's designated spots, they provide PCs with personality.
The newest range of such fans from Cougar is called Dual X. In addition to the normal, black models, there are green, red and blue versions.
All of them use dual-layer rigid blades, a diversion claws design (focused airflow and little turbulence), anti-vibration pads, and low-wear, high temperature lubricants, among other things. It is all part of the Hydraulic Bearing design. More information here, except for pricing and availability.