The Thinline 332; is a piezo-ceramic under-the-saddle pickup. Six electric crystals are imbedded in a piece of carbon graphite laminate to produce clear, dependable acoustic sound. Piezo (Piezoelectric) ceramic crystals emit an electric signal when pressed or vibrated. Fishman Transducers used this technology to design the “Thinline Series” pickups exclusively for C. F. Martin and Company. Works with any preamp Easy to install No changes to the body of the guitar Virtually eliminates feedback Stereo switching jack for optional stereo wiring