The BOSS CS-3 Compression Sustainer pedal compresses louder signals while boosting lower signals, providing smooth sustain without degrading the original sound quality. This is the perfect pedal for guitarists and bassists who want to sound their best.DC IN JackIt accepts the connection of an AC adaptor (PSA series). By using an Adaptor, you can play without being concerned about how much battery power you have left.Check IndicatorThis indicator shows whether the effects are on or off and also doubles as the battery check indicator. The indicator light when the effect is on.Input JackThis jack accepts input signals coming from a guitar, some other musical instrument, or another effects unit.Level and Tone KnobThe level knob adjusts the volume of the effect sound, and the tone knob adjusts the tone of the sound. Rotating it clockwise will create a sharp sound with emphasized treble while turning it counterclockwise will create a soft sound with cut treble.Output Jack and Pedal SwitchThe output jack is used to connect the unit to amplifiers or other devices. The pedal switch turns the effects on/off.ThumbscrewWhen this screw is loosened, the pedal will open, allowing you to change the battery.Attack Knob and Sustain KnobThis knob adjusts the intensity of the attack in the picking. The sustain knob adjusts the sustain time. Rotating this knob clockwise increases the sustain time. By rotating it counterclockwise, the outpost level is limited, therefore, the CS-3 works as a limiter.