These Wheelock motor bells use a high-quality, micro-motor operating mechanism. This provides long-term reliability, low starting voltage, and extremely low current consumption. These features enable the use of more bells per circuit and greater alarm signal distribution than conventional bells. The low starting voltage provides a stronger signal on marginal circuits. These motor bells eliminate the coils and contacts found in conventional vibratory bells. They contain a highly-efficient DC motor drive system to produce high sound pressure levels at lower current requirements. As a result, they reduce EMI generation problems. The operating mechanism is enclosed in a die-cast aluminum housing, making the bells suitable for both interior and exterior applications. The steel gong and striker last longer and produce a louder sound output.