This twin-head piezo transducer is designed for internal mount in acoustic guitars and other instruments. It is basically identical to the Twin Spot Classic but it comes with an endpin jack for internal mount. The jack can be mounted from the outside so no soldering is necessary. The twin-head system has distinctive advantages compared to the single-head transducer. The positioning at two spots results in a more balanced sound structure of the low and high frequencies. Thus the frequency range is wider compared to a single spot system. Technical Information: Pickup Head diameter: 1/2" Pickup Height: 1/32" Impedance: High ohmic Length of connection cables 1 ft. Jack: Shielded Endpin Jack (stereo type, connected mono) no soldering necessary