« virtual time keeper! »

This is an high quality metronome, most likely designed for use with piano though it could also be used with other acoustic instruments. Due to its design, I would assume that most people would like to place it atop their piano, as it has a classic, elegant look. The way that it functions is similar to the metronomes of old. The virtual pendulum swings back and forth and clicks in time to the appropriate setting of beats per minute. There is a lever that will allow you to adjust to the appropriate length. The clicks are loud enough to be heard even over the loudest piano passages, but still not overly loud.
This is especially appropriate for learning classical pianists, as it also has the Italian tempo terms (allegro, largo, andante) listed next to the BPM of that particular tempo. Thus, the student can get a familiarity with these tempos to the point where they most likely will not need the metronome after many years.
These are so well-built and timeless that they can last forever. In fact, my great aunt has had one at her piano for the last 30 years or so. Try doing that with an electric metronome!
This won't work well for electric guitarists, drummers, or other loud amplified instruments, but you bet it would be great for pianists, violinists (and all string instrument players), as well as horn players (though jazz saxophonists might actually drown it out). A great device that is timeless. I have been using this for about 2 or three years and it has really helped with my playing on beat. The device is very small and portable you can take it anywhere with you it fits right into your pocket. Its really a must have if you are a guitarist, you really need a handy device like this one. I highly recommend having one of these around you at all times.