20pcs 50MM Guitar Pickup Piezo Pickup Wired Amplifier with 6.35MM Output Jack for Acoustic GuitarThe sound pickup is a high-quality piezoelectric ceramic plate with a diameter of 50mmIt is very large and can pick up a wider range of sound in case you are not sure where the best parts of the sounds are. It's a pre-wired, pre-soldered piezoelectric harness and jack that makes it easy for you. All you have to do is connect the piezo or on your construction site, drill a hole and install the lift. So you're done! Fits most strings, musical instruments, such as guitar, mandolin, cigar box, guitar, violin, Ukulele, Banjo, etc. Installation instructions:1 remove the plastic film on the back of the pickup to reveal the adhesive2 place the pickup through the sound hole at the bottom of the front body where the guitar produces the best tonal response3 drill a hole from the inside of the body, loosen the plug socket, insert it into the hole and tighten the nutThe above procedures depend on different instruments. Specification:Color: Black Material: Metal + Plastic Long Cable: About 42cm / 16.5 inch Plug Diameter: About 6.35mm / 0.25 inch Package Contents: 20 x Piezoelectric Disk Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement error is +/- 1-3cm.