Anti-howling Circuit: by changing the audio frequency of the guitar pickup channel, suppress the howling of the resonant horn, so as to adapt to the installation and debugging of various types of guitars. USB Charging Interface: the charging interface on the pickup panel is convenient, simple and universal. Battery Capacity: built-in a removable and rechargeable lithium battery, full of electric resonance mode can be used continuously for more than 8 hours, stage mode can last more than 20 hours. Audio digital Effect: built-in high-speed high-fidelity audio digital module, configuring circuit to realize reverberation, the extension of sound effects such as chorus and delay, making the sound more flexible, transparent, broad and beautiful. Guitar Resonance Function: using the flat speakers attached to the inside of the guitar to make the guitar cabinet vibrate and sound, realizing sound effects, and increasing the resonance volume of the piano cabinet. BT Playback Circuit: which can connect the guitar to the audio signal of the BT device, and then play guitar accompaniment music or songs through the guitar itself or speakers, or download all kinds of audio files and play with the guitar through the Internet platform. Built-in omnidirectional microphone fingerboard. Material: ABS Mounting Hole: 12mm Item Size: 95.1 x 68.8 x 69.7mm / 3.74 x 2.71 x 2.74in Colour:Black Package Contents: 1 x sound pickup bar 1 x resonance speaker 1 x rotating cap 1 x opening sticker 1 x cable buckle 1 x charging cable (delivered Not included 1 18650 battery) 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.