[High quality] Made of copper, high temperature resistant, stable, durable and long service life [Size] Piezo pickups have a diameter of 27 mm ,Simple and easy to use, These pre-wired Piezo pickups can be easily installed in cigar box guitars, foot pedals and other homemade instruments for sound and vibration detection [Widely used] Very suitable for beginners as Press devices, electronic drum triggers, buzzers, making your own Press microphone, also used in watches, cameras, mobile phones, electronic toys, computers, etc. size:Copper sheet diameter 27mm Material:copper colour:Gold Package Contents: 15 x Acoustic 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.