Features: brand new and high quality Made of high-quality fiberglass board & electronic components materials, practical and durable. 5.1 bluetooth-compatible version, for DC 9-24V, 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 for DC for head with cable, which is for the input power interface of this product. Even if you don'for t have the for DC for head adapter or battery, you can connect it easily. This amp board has overheat for protection, circuit for protection, over-voltage and under-voltage for protection. Specifications: Material: Fiberglass Board + Electronic Components Size: approx 76x50x18mm/2.99x1.97x0.71 inches Package Includes: 1x Digital Power Amplifier Board 302 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.