3X Under Saddle Piezo Pickup Built-in Preamp System for Acoustic Guitar Meet the needs of acoustic guitars - Designed to meet the needs of acoustic guitars. The built-in preamp system offers a soundhole mounted preamp with rotary volume and tone formants. A quick, soldered-easy assembly-pickup is supplied as standard, ensuring quick, easy installation. Suitable for all steel guitars and nylon line.100 hours of continuous use-You can expect around 100 hours of continuous use between battery changes. Produce Excellent Bass--You can make 12 inch or 14 inch small size guitar to produce excellent bass.Great Gift for Music Lovers--Perfect for students, advanced players, music lovers, gift for kids. Mouthpiece Receiving, Sound Hole Adjustment ReceivingColor: BlackMaterial: ABS+PVC+Copper+IronSize: 58.9x47.4x25.3mm (L x W x H)Product Weight: 165gPackage Contents:3 x Main Body3 x Output Socket3 x Sucker3 x Battery Connection Port3 x Battery PackOnly 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.