E-Tremolo produce regular and repetitive variation in gain for the duration of a single note, which works like an auto-volume knob; this results in a swelling or fluttering sound effect.Features:Electric guitar tremolo effect pedal with true bypass.With 3 functional knobs to adjust the performance of the tremolo effect.LED light for indicating effects or bypass status.Full metal shell and compact size, durable and portable.Comes with a small pouch for convenient storage and carry.Functional Knobs:--LEVEL knob: adjusts the overall level of the output--DEPTH knob: controls the degree/depth of the tremolo--SPEED knob: controls the speed of the repetitive variation for the tremolo effectSpecifications:Input: 1/4" monaural Jack(impedance 2.2M Ohms)Output: 1/4" monaural Jack (impedance 10K Ohms)Current Draw: 30mAPower Supply: DC 9V AC adapter (center minus plug)Item Size: 9.5 * 4 * 3.5cm / 3.7 * 1.6 * 1.4inItem Weight: 140g / 4.9ozNote:Power Adapter is not included.Please use the power adapter whose polarity is positive pole outside and negative pole inside. Otherwise, the product may not work properly.Package List:1 * Effect Pedal1 * User Manual (English & Chinese)1 * Pouch