product has a percussion rhythm speed function: TAP function can accurately test your own heart beat speed or a song beat speed has two-channel headphone output. Features: back of product has a clip and lanyard hole results designed to facilitate fixed. Import sound unit beat sound is loud and sound is nice. Adjustable volume control. Stereo earphone jack is available. Tap function enables you to test your ideal tempo or tempo of a track. Multi-functional and professional metronome is lightweight and portable easy to use. Specifications: Color: yellow blue red white black (optional) Speed : 30-280bpm beat changes: 0 1 2 3 4 5 6 7 8 9 Accuracy: plus or minus 0.001 (thousandth) Volume adjustment: maximum volume medium volume minimum volume mute Battery: 1 * CR2032 3V 240mAh (not included) Item size: 130 * 56 * 32mm / 5.1 * 2.2 * 1.3in Item weight: 23g / 0.8ounce Package size:130 * 80 * 40mm / 5.1 * 3.1 * 1.6in Package weight: 33g / 1.2ounce Package list: 1 * Metronome 1 * User Manual