The Wheelock STH-15S-ULC supervised horn loudspeakers are equipped with a compression driver providing up to 15 watts RMS power handling capability, superior intelligibility and dispersion to achieve maximum sound projection and penetration.Weather-resistant metal construction and reentrant acoustic path assure protection against water, humidity and corrosion. The mounting bracket allows directional sound dispersion via vertical and horizontal positioning. Provisions are also included for surface or strap mounting to pillars and I-beams.All models include a built-in 25/70 V transformer featuring a screwdriver adjustable, 7-position watt/impedance selection switch. Wiring terminals are protected with a vandal-resistant adapter cover for control equipment utilizing cable or conduit.All models meet or exceed ULC’s requirements for speakers and are capable of operating within an ambient temperature range of 150° F (66° C) to –31° F (–35° C). Models comply with ULC Standard CAN/ULC-S541-2016 for speakers.