BOSS CS-3 Level, Tone, Attack, and Sustain Controls Compressor/Sustainer PedalThe 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 Jack It 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 Indicator This indicator