EFFECTS - Use this knob to control the volume level for the loop playback. | USE TO CONTROL - One knob cover Record, Overdub, Undo the loop,redo the loop, erasing, and store the current loop function. | LED INDICATOR - LED indicator shows the status of effect. No battery, Powered by AC adapter(not included). | ANTI SKID - Rubber pads on the backside is anti-skid, which enhances the stability and avoids friction. | RELIABLE QUALITY - High quality by aluminum alloy which is durable and have a classic mini size brings you a musical feast.