All Morley pedals use a 9 volt 300 mA regulated power supply. The center polarity is negative. Comes with handy LED to show that adapter is functioning. Available in USA or European version. Morley uses adapters other companies do not. If you use any other brand adapter, it may cause the Morley pedal to hum. Morley uses regulated adapters to minimize circuitry in our pedals. This helps maintain guitar tone and level and also prolongs battery life. Features include: · 9-volt 300 mA Regulated power supply (US and European Versions) · Center Polarity is negative · Handy LED shows adapter is working · Compatible with most other effect brands · Full color box with list of compatible brands