Made of alloy, strong and durable. Tcapo20 is not only a professional capo, but also a professional tuner. The tuner has high sensitivity, more precise, more precise, convenient and fast. The tuner automatically detects the sound and displays the name of the note accordingly. When the note name displayed on the screen matches the sound of the instrument, the precision bar points vertically to calibration "0" and the LED indicator turns green. If there is no operation or no signal input for 30 seconds, it will automatically enter power saving mode and the backlight will turn off. The backlight will return when there is an operation or signal input. Suitable for acoustic and electric guitars. Size: 7.5*1*11cm TUNING Range: A0 (27.5Hz) - C8 (4186Hz). A4 calibration: 430Hz --- 450Hz