?Features:Simulate the characteristic distortion and cabinet of a guitar amplifier.Extra amount of gain boost to higher frequency for greater distortion effect. Passive 3 band EQ for nature tone.True bypass design， minimizes tone loss and get more control of your pedal.Aluminum alloy housing， good durability.LED indicator shows status of effect and battery condition.The pedal can be powered by a battery or AC adapter.4 adjustable knob:Bass knob: control the amount of low frequencyGain knob: adjusts the amount of distortionHigh knob: control the amount of high frequencyLevel knob: control the level of the distorted signalSpecification:Color: BlackInput impedance: 1M OhmsOutput impedance: 10K OhmsPower: 9V battery or 9V AC adapter (not included)Product size: 11.7 * 6 * 3cm / 4.6 * 2.4 * 1.2inProduct weight: 238g / 8.4ozPackage size: 12.5 * 8.5 * 5.5cm / 4.9 * 3.3 * 2.2inPackage weight: 298g / 10.5ozPackage List:1 * As-4 effect pedal1 * User manual (English & Chinese)