Definitive Technology SR9040 High-Performance Bipolar Surround Speaker - (single speaker) High-performance Bipolar surround speaker: 50 Hz - 30 kHz Powerful L/R Bipolar speaker dispersion pattern for wider, more immersive surround sound Easy to use and built for unobtrusive placement in any room Iconic and visually powerful design features. Mounting type Keyhole hanger Totally inert, resonance-free cabinet structure (Includes only a single speaker)