The Bogen SPT15A Horn Loudspeaker is a compact, high intelligibility, reentrant type loudspeaker, designed for one-way or two-way sound and communication systems. Its sturdy, weatherproof, all metal construction is ideal for indoor and outdoor use in industrial plants, warehouses, schools, construction-sites, transportation terminals, and recreational areas. Screw terminals make installation fast and easy. The Model SPT15A Horn Loudspeaker has a built-in, variable impedance selector switch for matching the speaker power requirements to a 25V or 70V constant-voltage line.