This a small metronome that even with its small size produces a clear loud sound for convenientusage With a builted in rechargeable battery, it can used for long durations and can rechargedusing the USB adapter Professional small digital metronome, universals for most instruments that need rhythm or tempos, easy to use Clip & lanyard hole design for carry and easy to fix Clear LCD display and indicators light, with " select " & " up " or " down " adjuster for Rhythm Types, Tempos, rhythm & Volumes