Piezoelectric Sounders are sound components prepared by incorporating a piezoelectric vibration plate in a plastic case (resonator). Piezoelectric sounders are sound components which generate sound suitable for use as input signals (including multi-tone, melody and so forth) without built-in oscillation circuits. This characteristic allows them to be used in a wide range of applications. They come as the SMD type, which is optimal for small, high-density mounting and the pin type, which can be used for general purposes.