Overview: Piezo buzzers are used for making beeps, tones and alerts. This one is petite but loud! Drive it with 3-30V peak-to-peak square wave. To use, connect "-" pin to ground and the "S" pin to a square wave out from a timer or microcontroller. The middle pin of the module is not connected. For the loudest tones, stay around 4 KHz, but works quite well from 1.5KHz to 10KHz, though works best for tones between 1.5 to 2.5 kHz. For extra loudness, you can connect both pins to a microcontroller and swap which pin is high or low ('differential drive') for double the volume. They are usually used to generate tone, with enough software it can also be used to play music.