Description: Piezo elements come in handy when you need to detect vibration or a knock. You can use these for tap or knock sensors pretty easily by reading the voltage on the output. They can also be used for a very small audio transducer such as a buzzer.

• 30mm dimameter
• 3-12V working voltage

• Datasheet (7BB-20-6L0)
• Knock a Piezo with the Arduino
• KnockSensor tutorial
• Arduino MIDI Drum Kit with a piezo, from TodBot