The SPD-2C Sound Transducer with Built-In Generator from MPM is a type of signaling device with a current output of 1mA. It is designed to convert electrical pulses into acoustic signals. The device is mainly used in applications such as elevators, fire alarms, doorbells, and other types of warning/notification equipment. It is powered by a DC power supply and has a wide range of features, including low power consumption, a wide frequency response, and high sound pressure. The one-piece transducer is also highly reliable and easy to install, making it suitable for many types of applications.