This is a small 12mm round speaker that operates around the audible range. You can use these speakers to create simple music or user interfaces. Inside is a piezo plus the driver circuitry that makes it oscillate at 2KHz. On one hand, that makes it really great for integrating into projects because you don't need an oscillating control signal.
Specifications:
Sound Pressure Level: >85db
Resonant Frequency: 4,000± 300Hz
Rated Voltage: 5V
Operating Voltage: 4V~7V
Rated Current: <30mA
Operating Temperature Range: -20°C to +60 °C
Storage Temperature Range: -30°C to +85 °C
Dimensions (not including pins): 12mm diameter, 9.7mm tall
Pins: 6mm long and 0.3" apart