This is a typical plastic case piezo element, 13mm diameter, 3.5mm thick with self adhesive tape on the back.
A piezo element can be used to produce a simple sound by applying a pulse-width-modulation at appropriate frequencies, by changing the PWM frequency, you change the frequency of the sound, in this way you can play simple melodies.
Simply google for examples of using piezo elements (sometimes called piezo speakers)
All of our products are shipped from Christchurch, New Zealand using CourierPost for NZ, and Airmail for international.
