DOUBLE OS1 Resonance Pickup On-board Preamp SFT Same Frequency Trans Guitar Preamplifier System with Reverb Chorus Delay Rechargeable Li-ion Battery (Need Opening Holes to Install): The preamp also has a DOUBLE reverb effect module that allows you to create innovative sound via the transmission system driving the guitar body.Equipped with BT connection function it can be connected to your cellphone and play with the background .System pickup the guitar sound when you are playing the guitar and drives guitar body through its custom transmission device. When operated without an amplifier guitar body will increase its frequency response and the guitar sound will be more resonant solid and dynamic.It is a dual-pickup system with a piezo pickup and a microphone system not only interprets every detail of play but also adds extensity and dynamic to the sound of the guitar.The (Same Frequency Trans) guitar preamplifier is a masterpiece of innovation that has a transmission device which drives guitar body to phonate when you are playing. Specifications: Item Size: 90 * 50 * 45mm / 3.54 * 1.97 * 1.77in Package Weight: 357g / 12.59oz Battery: 1 * 2000mAh rechargeable battery Package Size: 17.5 * 12* 6cm / 6.89 * 4.7 *2.36in Item Weight: 207g / 7.30oz Material: ABS Package List: 1 * Vibrating Horn 1 * Pickup Wire 2 * Clip 1 * End-Pin Jack 1 * Type-Cable 1 * Pickup Note: This is an on-board preamp which needs opening holes to installation system. The use of a microphone requires connection to the speaker in order to be effective.