Share the same tempo, enhance your sense of rhythm and move in
  time. An earphone-type metronome that lets you practice while
  moving.
  The GM-1 is an ultra-compact metronome that you can place
  on one ear in the same way as with earphones. Use multiple GM-1
  devices and everyone listens so they can practice with the same
  tempo in sync. This makes it possible to use the GM-1 for group
  practice such as marching bands or dance teams, and for
  rehearsals where you need to move around. The canal-type earpiece
  fits comfortably and securely in your ear, letting you clearly
  hear the metronome sound amidst the ambient sound.
  - A metronome that synchronizes tempo across multiple
  devices—perfect for group practice.
  
 
  - Fits directly in your ear—the optimal device for musical
  instrument practice where you need to move around.
  
 
  - Canal type earpiece brings the metronome sound directly to
  your ear, making the sound easy to pick out.
  
 
  - Offers a wide variety of beats and rhythm variations—even odd
  meters are possible.
  
 
  - Use the jog switch to set the tempo intuitively.
  
 
  - Low power consumption for approximately 100 hours of
  continuous use.
  
 
  - A memory backup function that automatically saves your
  settings from the previous use.
  
 
  - Three sizes of earpieces (S, M and L) included.