The Boss DB-30 Dr. Beat Metronome makes it easy to accurately keep time during practice. Built small for slip-in-your-case portability, a headphone jack lets you hear the beat without bothering other people.
This metronome is easy to use but powerful, with a large LCD screen and the ability to handle time signatures up to 17 beats per measure. It's also got a built-in reference tone which is very helpful for tuning timpani and any other drum head.
More than just an adjustable click, this Dr. Beat can lay down 9 different patterns, 24 beat variations, rhythm styles, and combinations to play with.