The Intellitouch PT20 Clip On Tuner is the latest in vibration-based tuning. It"s automatic, chromatic, and displays the measured pitch on a large, backlit display for easy tuning. The PT20 tuner ignores background noise - it feels the instrument"s vibration instead of using sound. Works on electric and acoustic guitars, basses, violins, banjos, mandolins and more.Clips on Arrow display Multicolor backlight Strong clamp A-Ref adjustment 430Hz-450Hz Lifetime Warranty