Piezo elements are actually one of the coolest crystals you'll play with. Flex them, they generate a voltage (pretty high, actually). Pass power through them, and they'll flex. Do it fast enough, and they'll start to make a sound! So besides making annoying little beepy noises, you could use it as a sensor to detect a knock or other similar vibration.

Here's a handy element with leads that makes it convenient to mount in a breadboard.

Specifications:

• Operating Voltage(V): 1.0 ~ 20.0
• Rated Voltage(V): 3.0
• Dimension(mm): Ø12.5
• Total Height (mm): 6.3
• Capacitance (pF): 15,000
• Current Consumption (mA): ≤2
• Resonance Freq (Hz): 4,000
• Sound Pressure Level at 10cm(dB): ≥75
• Connection Method: Pin Type
• Self Drive: No

Please Note: These buzzers no longer come with long leads.