9 volt power supply for pedals, 200 ma power developed, and a fitting for connecting to a pedal or a garland. So very simple. As mentioned earlier, marking "Zero Hum" on the box is not a selling point. Before, I used a no name power supply, purchased from a DIY store, with choice of voltage, polarity, etc. ... Which still had $ 12 €. And I got a buzz with any pedal, sometimes very light (especially with my DS1), sometimes unbearable (FX600 Behringer and Digitech Grunge). I ended up disconnecting my pedals and no longer use them at all. With this power supply, no more buzz, even the three pedals on a cascading garland, no worries, even though the quality of some of my pedals could be poor (the behringer in mind). But not the slightest noise. Even with the gain on the DS1 background is a golden silence. So finally, if you are looking for a power supply for pedals that do not generate any noise, hurry on this one! In this way, it is certain that if there is noise, it comes from the wiring or the pedal itself, but this PSU is perfect. For 10 € I can not imagine what could blame him. I'll still play devil's advocate, just to split hairs in order not to 10, saying that a small voltage selector would have been nice (some pedals operate at 12 volts), and 200 m, while c is enough to power a big ten pedals, let's say a comfortable 500 Ma would have been the best of the best. Story not too much to pull the rind to feed a big pedal board. But it really does not get to 10. The balance is clearly positive you'll understand that this is an excellent power supply, no noise, plenty of power for ordinary people, what more?