http://www.amazon.com/Seiko-SQ50-V-Quartz-Metronome/dp/B000LFCXL8/ref=sr_1_1?ie=UTF8&qid=1391705671&sr=8-1&keywords=metronome
The updated SQ50 (red wheel, far right), finally gives us volume control of the beeping sound without having to pay a fortune and resort to draining our iphone/ipad battery with a metronome app. The blue version, left side, carries a louder beep (2 different pitches) which is good for young kids and the one in the middle, though credit card size, has a higher pitch beep if you're into that short of thing. Finally, a metronome I can be happy turning on and playing along with!
What is the metronome for besides the obvious, keeping steady? The metronome helps us diagnose the weaker areas of our playing so we can work for greater control. It helps us iron out our kinks! On a higher level, it fine tunes our listening and phrasing. On a more basic level, it organizes our practice time more efficiently.
Happy practicing!!