It is a big unit and I doubt it can be placed under the pedalboard because of its height (45 mm). It is a bit wider than a normal pedal, comparable with Behringer's Vintage Phaser and I placed on the board.
Inside you'll find a big toroidal transformer and all 5 outputs are independent and stabilized. You can't compare this tank with flimsy cheap electronic units. It has two LEDs one for power and one for overload. It comes with 10 cables for powering pedals (length without jacks - 60 cm), one daisy with 6 jacks, one cable for doubling the voltage and one cable for doubling the current. So you can power even a 18V pedal, or another hungry device which requires 500mA. With daisy cable you are no longer limited only of 5 pedals, you can power at least two more pedals, depending of consumption. The power unit is dead silent. None of my 5 pedals exhibits hiss, buzz or other kind of noises. Really, worth it any penny.