The Arion HU-8500 Stage Tuner is designed for use onstage next to guitar effect pedals. With LED lights and note indicator, you can tune accurately from a distance, even in the dark. 9 red LEDs light progressively closer to center as you approach true pitch. Center green LED lights when you're precisely in tune. Pitch adjuster selects base from 440Hz-445Hz. Tuning accuracy is within one cent. Low-impedance output for clear sound. The following power adapters work with the Arion HU-8500: Boss PSA-120 or Line 6 Tone DC-1.