Dayton Audio HDN-8 Weatherproof Sound Exciter Transducer Compact and extremely versatile, the HDN-8 Sound Exciter Transducer lets you create high-quality `hidden speakers¿ in walls, ceilings, floors, furniture, seating, and virtually any other surface you can think of resulting in great invisible sound. - Rugged plastic housing with flat black finish - Coarse-threaded mounting stud for single-point mounting into almost any material - Hermetically-sealed design for installation in wet or humid environments. 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. Specifications: Frequency response: 40 - 15,000 (typical) Sensitivity: varies by application Dimensions: 4" W x 1.75" H Impedance: 8 ohms Power handling: 50 watts RMS / 100 watts maximum.