The original and still one of the very best fan controllers on the market. The Sunbeam Rheobus takes you to a place of control unprecedented amongst other fan speed controllers. Fits into any standard 5.25" drive bay, the Rheobus not only allows you to control fans, but your CCFL light kits as well. What makes the Rheobus great is that you have full control from 0 to 12 volts across all 4 channels. Other fan controllers only allow you a range of 7 to 12 volts, but most of the time you will want to set your fans lower than that, and the Rheobus makes it happen. Another great feature of the Sunbeam Rheobus is that it can control your CCFL light kits as well, but not only as an on/off switch it allows you to control the brightness of your lights as well! The super bright color changing LED's are a great asset to see where your fan settings are. 0 to 7 volts the LED is red, and from 7 to 12 volts the LED turns blue, not only is this feature cool looking, it quickly allows you to see which of your fans are running on high voltage and which are running on low voltage.