The Roland PSB-120 Power Adaptor adds functionality to the Roland PCR-300 500 800 USB MIDI Keyboard Controllers and is also is a direct replacement for the Roland ACK-120 power supply. (The Roland ACK120 Power Adapter is the power supply for the Roland CM300, CM500, ep7mkII, ep9mkII, 707, JV, JW50, MV30, W50 keyboards.)