http://www.petersontuners.com/index.cfm?category=132 Just picked one of these up and it's very cool. Uses some type of piezo element to transfer the beat through vibration/pulse in addition to or in lieu of an audible click. I find it perfect for practicing with the lady without having the metronome have to be louder than the tv. It also makes you really feel the beat and internalize it. Very cool!