Quite a unit isn't it ? This is the reservoir and pump. Pretty much all the components are made out of plastic though. This unit can be placed in your 5.25" drive bays and functions as a reservoir, a pump, flow meter.

At the front side you'll spot a transparent window which makes it easy to check the coolant level. To the right, the smaller window is actually a water flow indicator. The reservoir will fit into two 5-inch bays of an ATX system case.

When we flip it around we stumble into a heap of connectivity. In and outflow for tubing, a Molex power connector (only one source required to power everything which is really good). Then two FAN headers (pulse-width modulation fan rotation speed), which you connect the two radiator fans to. Then sensors, you can plug in the flow control meters here. And last a USB connection which is needed for ESA support (control, monitoring and regulation over pump and fans).

Inside this unit you can also find the pump, this pump is capable of a 400 liter per hour flow rate.