My computer case has 5 front 5.25" drive bays unused so I try to fill them with useful stuff. This is very handy. I've installed many dockable drive bay enclosures but this is the first one to neatly provide two drives along with USB. Hence my recommendation.
As you can see from the press shots, you can pack quite a bit. The USB 3.0 front connectors connect directly to an available 19/20 pin USB 3.0 connector on your motherboard. The bay requires only one SATA power connector (it also comes with a MOLEX adapter) to power both drives.
You will also need two available free SATA ports.
The nice thing I like about it is the power switch that you can turn off and leave the drives off. You simply flip the switch to make the drives available when you need them.
Not all products are perfect so here are the cons I can think of:
There is no locking mechanism in the front.
There are no fan or cooling. The lack of fan may be an issue in the future for higher rpm drives and cases with inadequate air flow.
Here it is in my case:
And most importantly, it supports SATA 6.0 Gb/s. I've found other docks I've used in the past only support SATA II/ 3.0 Gb/s so this is a nice. Connecting directly to the SATA bus of the motherboard will always give better speed than USB 3.0 or eSATA.
Product Link on Amazon: