Prewired Piezo Ceramic Disc Element 27mm - 10 Pack
Now available from PMD Way are these Prewired Piezo Ceramic Disc Elements in packs of ten.
Click here for great value packs of 100!
These are a fun and useful part. 27mm in diameter, you can use them to create sound - just give them 5V and a PWM signal. Or they can be used as a knock sensor, check out the second half of the following video: