[BT Connectivity]: This wooden guitar soundhole pickup features a BT playback circuit that connects your guitar to any BT device. This allows you to play backing tracks or songs directly from your guitar, either in support mode or through a speaker. You can also download and play any type of audio file from the internet to accompany your guitar performance. [Built-in Tuner]: Our product comes with a built-in digital tuner, eliminating the need for additional tuning equipment. It features a high-speed, high-fidelity audio digital module and a high-quality circuit for reverb, delay, and other effects. This makes the sound more lively, transparent, broad, and beautiful. [Guitar Resonance Function]: The flat speaker attached inside the guitar vibrates the guitar body to produce sound, achieving sound effects and enhancing the resonance volume of the guitar body. When connected via BT, the guitar body can also be used as a small speaker. This product also has a powerful automatic feedback suppression function, so you don't have to worry about feedback during use. [Tail Nail Output and Charging Interface]: This pickup only requires a tail nail hole in the back of the guitar to achieve audio output and charging functions, making installation easy and quick. It also features an external baffle microphone design, which produces minimal coloration, strong and powerful baffle, and strong penetration. [Ultra-thin Miniature Design]: This pickup has an ultra-thin, miniature design and a simple soundhole installation method. It comes with a non-adhesive sticker that can be attached to the inside of the soundhole to complete the main unit installation. Guitar Sound Hole Applicable Range Size: Between 80mm and 105mm Colour:Black Material:ABS Size:8.7x6.8x2.8cm/3.4x2.7x1.1inch Package Contents: 1 x GuitarPickup Kit(Due to different product batches, the appearance , which does not affect the use) 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.