1. Use high-quality materials, 2. 10 , up to 1023 sound combinations 3. The Bluetooth name of each product can be changed, and multiple products can be easily identified 4. The volume of prompt tone can be adjusted to meet different needs of customers 5. Upgrade large chips, support AAC Bluetooth decoding, more lossless formats, low latency, support APP and Power amplifier chip: TPA3116D2 Bluetooth version: 5.1 Bluetooth transmission distance: 15 meters Audio input: Bluetooth+AUX+USB stick+USB sound card Audio output: mono 100W Adaptive power supply: DC7-24V, equal 4A (AC power is not allowed) Adapted horn: 20-100W, 3-8 Ω Volume adjustment: total volume with key click: play/pause double click: next song triple click: enter or exit mode long : turn off/on Protection mechanism: input anti-reverse connection, over-temperature, over-current, short circuit, anti-static protection Sound volume adjustment, on/off prompt tone, sleep aid song, firmware upgrade, etc. matching function and the true wireless function make the two sets of speakers can be combined to form a left and right channel box matching, with a stronger sense of spatial positioning. Colour:Black Material:abs delivered as separate parts, need to assemble by yourself Package Contents: 2x Bluetooth audio amplifier board module 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.