The disk works fine without extra power supply, so far no problems. And really mega small and thin. The metal case makes a solid impression. I 3.0 discs (but with separate power supply) possess other USB, I have to say though that this disk at the USB 3.0 speed is not nearly possible exploits, but felt more at USB 2.0 speed level is in comparison. Who can live with it, is well served with this disc.