Definitive Technology In-Wall RCS III Referance Ceiling Surround/Wall (Single, White) Single in-ceiling speaker Equipped with two 4.5-inch high-definition cast-basket bass/midrange and two 5.25x4.13-inch pressure-coupled low bass radiators Frequency response: 30Hz - 30kHz Equipped with one 1-inch pure aluminum dome tweeter Outer flange size: 11.5 W x 11.5 H inches