The SpectrAlert Advance series of notification appliances offers a wide range of indoor and outdoor speakers for wall and ceiling applications, indoors and outdoors. They are designed to be used at either 25 or 70.7 volts, and operate at any one for four input power levels. These products are electrically backward compatible with the previous generation of SpectrAlert speakers. With its low total harmonic distortion, the SpectrAlert Advance SP series offers high fidelity sound output. The SpectrAlert Advance SPV series offers greater sound output at every tap setting for applications with high ambient noise levels. Wall and ceiling products may be used interchangeably (wall products may be used on the ceiling and ceiling products may be used on the wall). K Series products are designed to be used over a wider range of temperatures and are suitable for use in wet locations.