The Bogen SPT30A and SP308A are compact, high intelligibility, reentrant type loudspeakers, designed for one-way or two-way sound and communication sys-tems. Their sturdy, weatherproof, all-metal construc-tion is ideal for indoor and outdoor use in industrial plants, warehouses, schools, construction sites, trans-portation terminals, and recreational areas. The Model SPT30A has a built-in, variable impedance selector switch for matching the speaker power requirements to a 25V or 70V constant-voltage line. The model SP308A has an 8-ohm impedance only.