This little black unit is really important because it helps you to keep in time and develop a feel for the beat !
The dial is divided in steps of 4bpm which is a very good choice because it prevents the display to be too cluttered (1 bpm isn't really that noticable when practicing).
I remember this well from my time when i studied classical music and piano, the mechanic metronome i used was identical in this case.
It starts at 40 and goes up to 208, a range that is broad enough for most music styles.
Acoustically the "beep" sound (there are two at choice here) is rather pleasant, due to the metronome using a Quartz instead of generating it the digital way.
I avoid the latter exactly because of the harsh bleep sounds these make, it gets on your nerves when practicing some hours.
You even get a visible sign on top of the metronome, a good help when practicing silent (for example without sound or with headphones !)
I recommend this unit to everyone who is playing an instrument, whether novice or pro.