This Sadducer is a passive under-saddle-transducer for acoustic guitar that uses six discrete piezo crystals, one for each string. The result is a high-output pickup designed for even frequency response. It’s exceptional for melody players, especially those who play over the entire fingerboard. But perhaps the biggest benefit is that, unlike other piezo pickups, the Sadducer is passive, and does not require a built-in or off-board preamp to boost and smooth the signal. That means no batteries required The steel string version is optimized for guitars with string spacing of 2.04″ to 2.30 (51.8 to 58.4mm) at the bridge. Its thin width profile accommodates both 18″ and 332″ saddles.We recommend that this pickup is installed by a qualified luthier.