Single Reference in-ceiling/in-wall surround speaker Equipped with two 4.5-Inch bass/mid drivers and two 4.5-Inch Planar pressure-coupled low bass radiators Frequency response: 26Hz - 30kHz.A/V Receiver Crossover Settings:Small (40 Hz) Equipped with two 1-inch pure aluminum dome tweeters Outer dimensions: 11 W x 12.75 H inches