Accepts All Atlas Sound and 1 3/8" - 18 Thread Compression Drivers with Throat Openings of 0.7" Dia. High-Efficiency Bi-Axial Horn Provides 130 degree x 60 degree Wide-Angle Sound Coverage Nominal Frequency Response of 350-8,000 Hz for High-Intelligibility Voice, Signaling and Full-Range Music in Indoor/Outdoor Applications Patented 180 degree Gimbal-Mount for Installation Flexibility Atlas Sound Model BIA-100 is the original reflex horn featuring a bi-axial design with twin air columns and exponential bell for wide-angle coverage with a linear frequency response. The horn provides excellent acoustic loading maintained to a 350 Hz low-frequency roll-off and optimizes delivery of high and mid-range signal levels. BIA-100 is designed for use with AtlasIED PD Series compression drivers and models having 13/8" -18 male threads and 0.707" dia. throat openings. The easily-mounted horn features the labor-saving patented gimbal-mount bracket assembly (U.S. Patent 4,325,529) which allows for directional positioning up to 180 degree vertically and horizontally. It includes a steel bracket, cast-mounting base and provisions for flange installation. The weather-resistant, non-glare matte black foam horn is resistant to resonance. Bracket assembly is finished in durable epoxy.