It is single-channel magnetic-pickup system that Features a soundhole mounted preamp with rotary controls for volume and tone. Features: Simple and novel, more ergonomic design brings more user-friendly control-method and more convenient installation experience, suitable for install in 96-104mm in diameter of acoustic guitar soundhole. Using high-purity self-adhesive copper wire, combined with RX winding technology, it brings lower noise sound. The coil is no longer expose the sound column, and the sound is thicker and more grainy. The exclusive design patent of the rotating battery compartment does not require additional battery packs or battery boxes, and the battery can be quickly and easily replaced without loosening the guitar strings, which is simple and convenient. The cork clip interface makes the installation more convenient, and there is no need to worry about the clip opening being too loose and slipping off anymore. Volume and tone adjustable design, suitable for various performance situations. Specifications: Material: ABS Suitable for: 96-104mm soundhole Power Supply: 2 * CR2032 battery, 3V, 220mAh Item Size: 149 * 60 * 33mm / 5.87 * 2.36 * 1.30in Item Weight: 147g / 5.19oz Package Weight: 315g / 11.13oz Package Size: 18 * 12 * 6.5cm / 7.09 * 4.72 * 2.56in Package List: 1 * Guitar Pick-up 1 * Output Tail-pin 1 * Tail-pin Leather Sheath 1 * Screwdriver 2 * Gasket 2 * Cable Cleat 1 * Manual (English)