The sound pickup is a high-quality 50mm piezoelectric ceramic disc transducer. It is large and capable of capturing a wide range of sound, which is helpful when determining optimal sound collection points. This is a pre-wired and pre-soldered piezo transducer with a jack harness for easy installation. Simply attach the piezo to your instrument, drill a hole, and mount the jack. Compatible with most string instruments such as guitar, mandolin, cigar box guitar, violin, ukulele, banjo, and others. Installation instructions: 1. Remove the plastic film from the back of the transducer to expose the adhesive. 2. Place the transducer through the sound hole to the lower part of the front body where the instrument produces the best tonal response. 3. Drill a hole from inside the body, loosen the end-pin jack nut, insert the jack into the hole, and tighten the nut. Note: Installation may vary depending on the instrument. Specifications: Color: Black Material: Metal + Plastic Cable length: Approx 42cm / 16.5 inches Plug diameter: Approx 6.35mm / 0.25 inches Package Contents: 2 x Disc piezo pickups Note: Light reflection and differences in display screens may cause slight color variations between the product image and the actual item. Measurement error allowance is +/- 1-3cm.