The sound pickup is high-quality 50mm Piezoelectric ceramic disc transducer It is very large and can collect a range of sound in case you are not sure where are the best parts of the sounds. This is a pre-wired, pre-soldered piezo and jack harness which easy . All you have to do is to attach the piezo in or on your build, drill a hole and mount the jack. Then you're done! Fit for most string music instruments such as Guitar Mandolin Guitar Violin Ukulele Banjo, etc. Installation instruction: 1 Take the plastic film down from the back of transducer to expose the adhesive 2 Place the transducer through the sound hole to the lower part of the front body where the guitar produces the best response 3 Drill a hole from inside the body, loosen -pin jack nut, insert it to the hole and tighten the nut The above procedures depend on different instruments. Specification: color:black Material: metal + plastic Cable long: 42cm/16.5 inch Plug Dia: 6.35mm/0.25 inch Package Contents: 12 x Disc piezo pickup Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.