Mooer Yellow Comp Optical Compression Pedal w/ Power Supply Includes a Power Supply! Input: 1/4" monaural jack (impedance: 470k ) Output: 1/4" monaural jack (impedance: 1k Ohms) Power Requirements: AC adapter 9V DC (center negative plug) Dimensions: 93.5mm (D) - 42mm (W) - 52mm (H)