The MA-30 is the latest offering from Korg's innovative line of metronomes, with new features like volume control and sophisticated rhythms such as triplets and quadruplets with inner beats omitted. Powered by 2 AA batteries and with a jack for adding an optional headphone, you can take the MA-30 with you when playing or practicing anywhere. It's simple to use and has an easy to read LCD screen. Tempo adjusts from 40-208 bpm Tap function for setting the tempo Earphone jack so only you can hear it Memory backup function Approximately 250 hours of continuous use using 2 AA batteries (batteries are not included) Unit Dimensions - 4.09(W) x 2.52(D)x 0.59 (H) inch / Weight - 0.17 lbs. (including batteries)