With built - in power supply and two MO65 moving coil meters, workable on 230 volts AC fitted with triode valve on front panel. Consist of Hight voltage : 0-300 volts AC at 30 mA continously variable Bias : 0-15 volts DC at 5mA continously variable.Low voltage : 6.3 volts AC at 2 amps with built in rheostat for filament current control.