Described by Dayton Audio:
Unlike a tactile transducer that delivers shake effects to your listening experience, the HDN-8 Sound Exciter Transducer is a full range, versatile, compact transducer that can excite a surface or structure over a wide bandwidth, enabling the creation of completely hidden audio systems in walls, ceilings, and floors. Its high power handling allows it to produce useful sound levels with a small number of transducers, and its hermetically-sealed design permits indoor or outdoor installation, even in wet or humid environments such as outside decking or an inside bath/shower installations. It features a single, coarse-threaded mounting stud that easily installs into wood, fiberglass, or plastic, and the 8-ohm impedance allows integration with conventional audio amplifiers.
Dimensions: 4″ W x 1.75″ H