I installed three sets of fans in my media cabinet and used one of these splitters so that I only needed two outlets. Now I have an extra power supply, should one go bad.
If you are like me, you hate wasting outlets. Since the 2A AC adapter required for most cooler guys controllers use molex power and 2A is enough juice to power 4 fans (at least the ones I use), this splitter allows me to power to panels with one AC adapter. Nicely molded so you dont see ugly wires. Seats well.