A compact dedicated guitar/bass tuner with new circular display The GT-4 is a dedicated guitar and bass tuner that automatically detects an instrument's pitch, which offers simple operation. With a large note name display in the center and red LEDs that rotate in a circular pattern, the Korg GT-4 is a revolutionary guitar tuner with optimal visibility. This bass and guitar tuner supports seven-string guitars (7B through 1E) in Guitar mode, and six-string basses (Low-B and Hi-C) in Bass mode. While compact, it instantly indicates the pitch with the high precision you expect from KORG. The built-in high-sensitivity microphone supports tuning of acoustic guitars as well.