100% brand new and high quality Made of high-quality fiberglass board & electronic components materials, practical and durable. 5.1 bluetooth-compatible version, DC 12-24V, 2.1 Channel, transmission efficiency is higher, transmission distance is longer. Potentiometer to adjust the volume, with a switch, easy to control the volume, very suitable for DIY speakers. It comes with a DC head with cable, which is compatible with the input power interface of this product. Even if you don't have the DC head adapter or battery, you can connect it easily. This amp board has overheat protection, circuit protection, over-voltage and under-voltage protection. Specifications: Material: Fiberglass Board + Electronic Components Size: approx 119x100x22x10mm/4.69x3.94x0.87x0.39 inches Note: 1.Please allow 1-3cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package Includes: 1x Digital Power Amplifier Board TB21S Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-Dadangjia