a4 frequency selection: 430hz-450hz, generally choose 440hz battery: 1 cr2032 (no delivery battery) colour: black product weight: about 25g brand: eno package include:1 * electronic tuner size: 3.2*4.6*4.5cm (1.26*1.81*1.77in) item type:electronic tuner adjustment range: a0 (27.5hz)-c8 (4186hz) adjustment options: violin, viola, cello, double bass, etc. Small and Exquisite appearance, convenient to carry. Silicone pickup clip, does not harm your instrument. 360 degree rotatable design to match your need better. Tuning Fast. Quasi. Steady. It can be used for the tuning of Violin, Viola ,Cello ,Double Bass.