The D’Addario Pedal Tuner Plus boasts the speed and accuracy of our original Pedal Tuner, plus two new features. First, it has a high-quality signal buffer, to maintain your sound across long cable runs and prevent signal loss through your effects chain. Second, it includes a programmable countdown timer to keep track of your set or session time. All of that combines to make a standout multipurpose pedalboard tool — keeping you in tune and on time. D’Addario electronic tuners are designed by musicians for musicians featuring intuitive features, easy to read display's, and exceptional tuning accuracy., Onboard Signal Buffer, 32-Bit Processor for Fast Response and Accurate Tuning, Countdown Stage Timer, Full-Color Vertical Display / Power Requirements: 9V Battery or 9VDC (300mA) Power Supply, Reference Pitch: A4 = 440 Hz / Calibration Range: 415 - 475 Hz