The features are:

Battery powered
Lightweight design
Built in mic and input jack
Power supply: Two AAA batteries 1.5 V (included)
Battery life: Approximately 100 hours
Controls: Power, note, function, mode
Sensitivity: LED needle tuning indicator plus upper and lower (flat and sharp) and 'in tune' lights
Dimensions: 4.02"(102mm) Wide x 2.52"(64mm) Deep x 0.92" (23mm) High