• Chromatic and Guitar/Bass modes, with support for 7-string guitars and 6-string basses. Modes Chromatic. Chromatic flat x2. The display and tuning functions are identical to the TU-3—the only thing missing is the pedal switch, so it's on and ready to go, the TU-3S is perfect for use with pedal switching systems such as the BOSS ES-8 and ES-5, and ideal for any setup where space is valuable.